U.S. patent application number 15/643803 was filed with the patent office on 2017-10-26 for fuel markers and methods of producing and using same.
The applicant listed for this patent is Authentix, Inc.. Invention is credited to John-Christopher BOYER, Jeffrey L. CONROY, Philip B. FORSHEE.
Application Number | 20170306255 15/643803 |
Document ID | / |
Family ID | 56100480 |
Filed Date | 2017-10-26 |
United States Patent
Application |
20170306255 |
Kind Code |
A1 |
CONROY; Jeffrey L. ; et
al. |
October 26, 2017 |
Fuel Markers and Methods of Producing and Using Same
Abstract
A composition comprising a fuel and at least one compound
characterized by Formula I: ##STR00001## wherein X is carbon,
oxygen, or sulfur; R.sup.1 and R.sup.2 each independently are
hydrogen, a C.sub.1 to C.sub.20 alkyl, or a C.sub.6 to C.sub.10
aryl; R.sup.3 and R.sup.3' each independently are hydrogen or a
C.sub.1 to C.sub.4 alkyl; R.sup.4 and R.sup.4' each independently
are hydrogen, a C.sub.1 to C.sub.4 alkyl, a C.sub.4 to C.sub.10
cycloalkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.5 and R.sup.5'
each independently are a C.sub.4 to C.sub.10 alkyl; R.sup.6 and
R.sup.6' each independently are hydrogen or a C.sub.1 to C.sub.6
alkyl; and R.sup.7 and R.sup.7' each independently are hydrogen or
a C.sub.1 to C.sub.4 alkyl; and wherein the compound of Formula I
when subjected to GC-MS using electron ionization at greater than
about 70 eV produces at least one ion having a mass-to-charge ratio
of from 300 to 600.
Inventors: |
CONROY; Jeffrey L.; (Allen,
TX) ; FORSHEE; Philip B.; (McKinney, TX) ;
BOYER; John-Christopher; (Dallas, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Authentix, Inc. |
Addison |
TX |
US |
|
|
Family ID: |
56100480 |
Appl. No.: |
15/643803 |
Filed: |
July 7, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14806381 |
Jul 22, 2015 |
9732296 |
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15643803 |
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62136068 |
Mar 20, 2015 |
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62194088 |
Jul 17, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10L 1/1608 20130101;
C10L 2200/0263 20130101; C10L 1/003 20130101; G01N 2030/025
20130101; C07C 323/20 20130101; C10L 2200/0446 20130101; C07C 43/21
20130101; C07C 43/263 20130101; C07C 2601/14 20170501; C07C 43/2055
20130101; C10L 1/2406 20130101; C07C 43/275 20130101; C07C 321/30
20130101; C07B 2200/05 20130101; C10L 2230/16 20130101; G01N 24/08
20130101; C07C 2601/16 20170501; G01N 21/65 20130101; C10L 1/1852
20130101; G01N 33/22 20130101; C10L 1/2412 20130101; G01N 30/7206
20130101; C10L 10/00 20130101 |
International
Class: |
C10L 1/24 20060101
C10L001/24; C07C 43/205 20060101 C07C043/205; C07C 43/21 20060101
C07C043/21; C07C 43/263 20060101 C07C043/263; C07C 43/275 20060101
C07C043/275; C07C 321/30 20060101 C07C321/30; G01N 30/72 20060101
G01N030/72; G01N 21/65 20060101 G01N021/65; C10L 10/00 20060101
C10L010/00; C10L 1/24 20060101 C10L001/24; C10L 1/185 20060101
C10L001/185; C07C 323/20 20060101 C07C323/20; G01N 33/22 20060101
G01N033/22 |
Claims
1. A compound characterized by Formula I: ##STR00040## wherein X
can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and R.sup.2
can each independently be hydrogen, a C.sub.1 to C.sub.20 alkyl
group, or a C.sub.6 to C.sub.10 aryl group; R.sup.3 and R.sup.3'
can each independently be hydrogen or a C.sub.1 to C.sub.4 alkyl
group; R.sup.4 and R.sup.4' can each independently be hydrogen, a
C.sub.1 to C.sub.4 alkyl group, a C.sub.4 to C.sub.10 cycloalkyl
group, or a C.sub.6 to C.sub.10 aryl group; R.sup.5 and R.sup.5'
can each independently be a C.sub.4 to C.sub.10 alkyl group;
R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.6 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group; and
wherein the compound characterized by Formula I when subjected to
gas chromatography-mass spectrometry (GC-MS) using electron
ionization produces at least one ion having a mass-to-charge ratio
of greater than about 300 at an ionization energy of equal to or
greater than about 70 eV.
2. The compound of claim 1 wherein X is O or S and R.sup.1 and
R.sup.2 are lone non-bonding electron pairs.
3. The compound of claim 1 wherein the compound characterized by
Formula I has Structure A: ##STR00041##
4. The compound of claim 1 wherein the compound characterized by
Formula I has Structures B-F: ##STR00042##
5. The compound of claim 1 wherein X is C and R.sup.1 and R.sup.2
each independently are selected from the group consisting of a
methyl group, an ethyl group, a n-propyl group, an iso-propyl
group, a n-butyl group, an iso-butyl group, a sec-butyl group, a
tert-butyl group, a pentyl group, a n-pentyl group, an iso-pentyl
group, a sec-pentyl group, a hexyl group, a heptyl group, an octyl
group, a nonyl group, a decyl group, a undecyl group, a dodecyl
group, a tridecyl group, a tetradecyl group, a pentadecyl group, a
hexadecyl group, a heptadecyl group, an octadecyl group and a
nonadecyl group.
6. The compound of claim 1 wherein the compound characterized by
Formula I has any of Structures G-O: ##STR00043## ##STR00044##
7. The compound of claim 1 wherein X is C and R.sup.1 and R.sup.2
can each independently be hydrogen, a C.sub.1 to C.sub.10 alkyl
group, or a C.sub.6 to C.sub.10 aryl group.
8. The compound of claim 7 wherein the C.sub.6 to C.sub.10 aryl
group is phenyl, a substituted phenyl, tolyl, a substituted tolyl,
xylyl or a substituted xylyl.
9. The compound of claim 7 wherein the compound characterized by
Formula I has Structure P: ##STR00045##
10. The compound of claim 1 wherein X is C and R.sup.3 and R.sup.3'
can each independently be a methyl group or hydrogen.
11. The compound of claim 1 wherein X is C and R.sup.4 and R.sup.4'
can each independently be a C.sub.1 to C.sub.4 alkyl group, a
C.sub.4 to C.sub.10 cycloalkyl group, or a C.sub.6 to C.sub.10 aryl
group.
12. The compound of claim 11 wherein the C.sub.4 to C.sub.10
cycloalkyl group is a cyclobutyl group, a substituted cyclobutyl
group, a cyclopentyl group, a substituted cyclopentyl group, a
cyclohexyl group, a substituted cyclohexyl group, a cycloheptyl
group, a substituted cycloheptyl group, a cyclooctyl group, or a
substituted cyclooctyl group.
13. The compound of claim 1 wherein R.sup.4 and R.sup.4' are
hydrogen.
14. The compound of claim 1 wherein R.sup.4 and R.sup.4' can each
independently be hydrogen or a tert-butyl group.
15. The compound of claim 1 wherein X is C, R.sup.1 and R.sup.2 are
a methyl group, and R.sup.5 and R.sup.5' are both a C.sub.4 to
C.sub.10 alkyl group.
16. The compound of claim 1 wherein R.sup.5 and R.sup.5' are both a
pentyl group or a heptyl group.
17. The compound of claim 1 wherein R.sup.6 and R.sup.6' each
independently are selected from the group consisting of a methyl
group, an ethyl group, a n-propyl group, an iso-propyl group, a
n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl
group, a pentyl group, a n-pentyl group, an iso-pentyl group, a
sec-pentyl group and a hexyl group.
18. The compound of claim 1 wherein X is O and R.sup.5 and R.sup.5'
are a heptyl group.
19. The compound of claim 1 wherein X is O or S and R.sup.3,
R.sup.3', R.sup.7 and R.sup.7' can each independently be hydrogen
or a methyl group.
20. The compound of claim 1 wherein the compound characterized by
Formula I is soluble in a solvent characterized by a flash point
greater than about 60.degree. C.; wherein the solvent is miscible
with a fuel; and wherein the compound characterized by Formula I is
characterized by a solubility in the solvent of equal to or greater
than about 50% at 25.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of and claims
priority to U.S. patent application Ser. No. 14/806,381, filed Jul.
22, 2015, published as U.S. Patent Application Publication No. US
2016/0272905 A1, which is a non-provisional of and claims priority
to U.S. Provisional Application Nos. 62/136,068 filed Mar. 20, 2015
and 62/194,088, filed on Jul. 17, 2015 and entitled "Fuel Markers
and Methods of Producing and Using Same," each of which is
incorporated by reference herein in its entirety.
[0002] The present application is related to U.S. patent
application Ser. No. 14/806,389 (now U.S. Pat. No. 9,631,152) and
Ser. No. 14/806,404 (now U.S. Pat. No. 9,366,661), both filed Jul.
22, 2015, each of which is a non-provisional of and claims priority
to U.S. Provisional Application Nos. 62/136,068 filed Mar. 20, 2015
and 62/194,088, filed on Jul. 17, 2015 and entitled "Fuel Markers
and Methods of Producing and Using Same," each of which is
incorporated by reference herein in its entirety.
[0003] The present application is also related to U.S. patent
application Ser. No. 15/051,196 filed Feb. 23, 2016, published as
U.S. Patent Application Publication No. US 2016/0272907 A1, now
abandoned, which is a continuation of and claims priority to U.S.
patent application Ser. Nos. 14/806,381, 14/806,389 (now U.S. Pat.
No. 9,631,152) and Ser. No. 14/806,404 (now U.S. Pat. No.
9,366,661), all filed Jul. 22, 2015, each of which is a
non-provisional of and claims priority to U.S. Provisional
Application Nos. 62/136,068 filed Mar. 20, 2015 and 62/194,088,
filed on Jul. 17, 2015 and entitled "Fuel Markers and Methods of
Producing and Using Same," each of which is incorporated by
reference herein in its entirety.
TECHNICAL FIELD
[0004] The present disclosure relates to fuel compositions, more
specifically marked fuel compositions and methods of producing and
using same.
BACKGROUND
[0005] Fuels represent a crucial energy supply and an important
revenue source. Based on their provenience and quality (e.g.,
different grades or types of fuel), fuels can be differentially
priced, such as taxed fuel and subsidized fuel or tax-free fuel;
kerosene; diesel fuel; low-octane gasoline; high-octane gasoline;
etc. Fuels can be differentially priced for a variety of reasons.
In some countries, liquid fuel, such as diesel fuel, kerosene, and
liquefied petroleum gas, is subsidized or sold below market rates
to provide more widespread access to resources. Fuel can also be
subsidized to protect certain industry sectors, such as public
transportation.
[0006] Fuel adulteration is a clandestine and profit-oriented
operation that is conducted for financial gain, which operation is
detrimental to the rightful owner. Sometimes, fuels can be
adulterated by mixing together fuels from different sources to
obscure the origin of one or more of the fuels. Other times,
adulterated fuels can be obtained by mixing higher priced fuel with
lower priced fuel (e.g., lower grade fuel) or adulterants such as
solvents. In some cases, subsidized fuel can be purchased and then
re-sold, sometimes illegally, at a higher price. For example,
subsidized fuel can be purchased and then mixed with other fuel to
disguise the origin of the subsidized fuel.
[0007] Fuel markers can be added to fuels to establish ownership
and/or origin of fuel. However, some markers placed in fuel for
authentication can sometimes be at least partially removed to
disguise the origin of the fuel. While some methods have employed
the use of deuterated structures as fuel markers, such methods do
not use of deuterated isotopologues to improve the accuracy of
analysis.
[0008] Fuel adulteration can be assessed by determining the
presence and concentration of fuel markers in a fuel sample via a
variety of analytical techniques, such as gas chromatography (GC),
mass spectrometry (MS), etc. Fuel markers can interact with their
immediate environment (e.g., matrix), such as fuel, solvent,
masking agents, etc., surrounding the marker, and the effect of the
matrix can hinder the analysis of a fuel sample for determining
whether a fuel is adulterated or not. While most prominently
reported in trace level analysis of pesticide residues, matrix
effects have been attributed to matrix components which cannot be
efficiently separated from analytes of interest via a specified
sample preparation methodology.
[0009] There have been a variety of approaches to mitigate matrix
effects, such as for example pulsed inlet conditions, matrix
matched standards, inclusion of analyte protectants in analytical
samples, etc. While these approaches could improve detectability of
target analytes (e.g., fuel markers) in some instances, their
application to routine analyses proves rather complicated from a
practical point of view. These approaches are usually neither
generally applicable to a wide variety of chemical classes of fuel
marker, nor desirable as they would add significant cost, time and
complexity to the analysis.
[0010] Another approach to mitigate matrix effects can employ
"matrix matched standards," where standards can be prepared from
the same matrix to be analyzed. While this approach can represent a
way to reliably correct for matrix effects, a diverse matrix in
combination with the lack of a priori knowledge of what problematic
components are present in the matrix can prevent this approach from
being an effective solution.
[0011] Yet another approach to mitigate matrix effects can employ
analyte spiking (also known as "method of standard addition"),
which entails adding known amounts of a standard to one or more
aliquots of an unknown sample. This approach can generate a
standard curve where the y-intercept of the linear regression fit
of the collected data represents the endogenous concentration of
the analyte (e.g., fuel marker) in the sample. While theoretically
this approach could work, practically it entails too high of a cost
in terms of time (requires 2-4 additional analyses per unknown
sample) and the analysis of the data can be considered too complex
for the practical purpose of fuel authentication.
[0012] Existing analytical approaches to determine fuel
adulteration and mitigate matrix effects all have significant
limitations that preclude their utility in fuel authentication.
Thus, there is an ongoing need to develop and/or improve fuel
markers and methods for detecting these markers.
BRIEF SUMMARY
[0013] Disclosed herein is a composition comprising (a) a fuel and
(b) at least one compound characterized by Formula I:
##STR00002##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.20
alkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.3 and
R.sup.3' can each independently be hydrogen or a C.sub.1 to C.sub.4
alkyl group; R.sup.4 and R.sup.4' can each independently be
hydrogen, a C.sub.1 to C.sub.4 alkyl group, a C.sub.4 to C.sub.10
cycloalkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.5 and
R.sup.5' can each independently be a C.sub.4 to C.sub.10 alkyl
group; R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.6 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group; and
wherein the compound characterized by Formula I when subjected to
gas chromatography-mass spectrometry (GC-MS) using electron
ionization produces at least one ion having a mass-to-charge ratio
of from about 300 to about 600 at an ionization energy of equal to
or greater than about 70 eV.
[0014] Also disclosed herein is a compound characterized by Formula
I:
##STR00003##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.20
alkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.3 and
R.sup.3' can each independently be hydrogen or a C.sub.1 to C.sub.4
alkyl group; R.sup.4 and R.sup.4' can each independently be
hydrogen, a C.sub.1 to C.sub.4 alkyl group, a C.sub.4 to C.sub.10
cycloalkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.5 and
R.sup.5' can each independently be a C.sub.4 to C.sub.10 alkyl
group; R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.6 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group; and
wherein the compound characterized by Formula I when subjected to
gas chromatography-mass spectrometry (GC-MS) using electron
ionization produces at least one ion having a mass-to-charge ratio
of greater than about 300 at an ionization energy of equal to or
greater than about 70 eV.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] For a more complete understanding of the present disclosure
and advantages thereof, reference will now be made to the
accompanying drawings/figures in which:
[0016] FIG. 1 displays a graph of calculated fuel marker
concentrations for several diesel fuel samples;
[0017] FIG. 2 displays ion chromatograms for fuel markers in
different diesel fuel samples;
[0018] FIG. 3A displays ion chromatograms of a fuel marker in
different diesel fuel samples prior to solid phase extraction;
and
[0019] FIG. 3B displays ion chromatograms of a fuel marker in
different diesel fuel samples subsequent to solid phase
extraction.
DETAILED DESCRIPTION
[0020] Disclosed herein are marked fuel compositions and methods of
determining adulteration of same. In an embodiment, a marked fuel
composition can comprise a fuel and a fuel marker, wherein the fuel
marker comprises at least one compound characterized by Formula
I:
##STR00004##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.20
alkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.3 and
R.sup.3' can each independently be hydrogen or a C.sub.1 to C.sub.4
alkyl group; R.sup.4 and R.sup.4' can each independently be
hydrogen, a C.sub.1 to C.sub.4 alkyl group, a C.sub.4 to C.sub.10
cycloalkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.5 and
R.sup.5' can each independently be a C.sub.4 to C.sub.10 alkyl
group; R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.6 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group. The
compound characterized by Formula I can be further subjected to gas
chromatography-mass spectrometry (GC-MS) using electron ionization,
wherein the compound characterized by Formula I produces at least
one ion having a mass-to-charge ratio of from about 300 to about
600 at an ionization energy of equal to or greater than about 70
eV.
[0021] In an embodiment, a method of the present disclosure can
comprise contacting (a) a fuel and (b) at least one compound
characterized by Formula I to yield a marked fuel composition. In
an embodiment, the method can further comprise subjecting the
marked fuel composition to an analytical technique for determining
adulteration of the fuel. As used herein, "adulteration" of a fuel
refers to altering, mixing, diluting, laundering, etc., of the
fuel. In some cases, a fuel (e.g., a fuel taxed at a higher rate)
can be combined (e.g., illegally) "as is" with another fuel (e.g.,
an untaxed fuel or fuel taxed at a lower rate) or solvent to form
an adulterated (e.g., altered, mixed, diluted, laundered, etc.)
fuel. For example, a fuel can be mixed with one or more other
fuels, solvents, and the like, or combinations thereof. If
undetected, the adulterated fuel can be sold, sometimes illegally,
at the price of the fuel taxed at the higher rate to yield a
profit. In some instances, the adulterated fuel can be potentially
hazardous for the user, such as for example when a hazardous
solvent is used for adulterating the fuel. In other instances, the
fuel can be treated or "laundered" in an attempt to remove
identifying features such as markers from the fuel (e.g., to
disguise the origin of the fuel, the amount of tax paid on the
fuel, etc.) before the fuel is mixed with another fuel to form an
adulterated fuel.
[0022] In an embodiment, a method of determining adulteration of a
fuel comprises subjecting to an analytical technique a marked fuel
mixture comprising (a) a fuel; (b) a compound characterized by
Formula I; and (c) a heavy compound, wherein the heavy compound
comprises a compound of Formula I having at least one atom replaced
with an isotope tag. Generally, an isotope tag refers to an isotope
of a particular atom that replaced such particular atom in a
molecule, as will be described in more detail later herein.
[0023] In an embodiment, a method of determining adulteration of a
fuel further comprises (i) acquiring a fuel sample; (ii) adding a
known amount of the heavy compound to the fuel sample to yield a
marked fuel mixture; (iii) subjecting the marked fuel mixture to
the analytical technique to record an analytical signal for the
compound characterized by Formula I and an analytical signal for
the heavy compound; (iv) comparing the analytical signal for the
known amount of heavy compound to the analytical signal for the
compound characterized by Formula I; (v) determining a ratio of an
amount of the compound characterized by Formula I to the known
amount of the heavy compound in the marked fuel mixture; and (vi)
calculating the amount of the compound characterized by Formula I
in the marked fuel mixture. As will be appreciated by one of skill
in the art, and with the help of this disclosure, "amount" can
refer to any suitable ways of expressing how much compound (e.g.,
fuel marker, heavy compound, etc.) is present in a composition
(e.g., marked fuel composition, marked fuel mixture, etc.), such as
for example concentration, molarity, molality, percent composition,
mole fraction, weight fraction, parts per million (ppm), parts per
billion (ppb), etc. For purposes of the disclosure herein, ppb and
ppm are expressed as mass/mass (m/m), unless otherwise
specified.
[0024] In an embodiment, a method of determining adulteration of a
fuel comprises (i) contacting a fuel sample with a heavy compound
to form a marked fuel mixture, wherein the fuel sample comprises a
fuel and a compound characterized by Formula I, and wherein the
heavy compound comprises the compound of Formula I having at least
one atom replaced with an isotope tag; (ii) subjecting the marked
fuel mixture to solid phase extraction (SPE) to yield a marked fuel
mixture fraction, wherein at least a portion of the compound
characterized by Formula I and at least a portion of the heavy
compound elute together in the marked fuel mixture fraction; and
(iii) subjecting to an analytical technique the marked fuel mixture
fraction to determine fuel adulteration. In such an embodiment, the
analytical technique comprises GC-MS using electron ionization,
wherein the compound characterized by Formula I can produce at
least one ion having a mass-to-charge ratio of from about 300 to
about 600 at an ionization energy of equal to or greater than about
70 eV.
[0025] While the present disclosure will be discussed in detail in
the context of a method of determining adulteration of a fuel, it
should be understood that such method or any steps thereof can be
applied in a method of authenticating any other suitable liquid
mixture. The liquid mixture can comprise any liquid mixture
compatible with the disclosed methods and materials. As used
herein, "authenticating" of a fuel or any other suitable liquid
mixture refers to determining whether the fuel or any other
suitable liquid mixture has been adulterated. Authenticating of a
fuel or any other suitable liquid mixture can comprise detecting
the presence and amount (e.g., concentration) of markers (e.g.,
fuel markers) in the fuel or any other suitable liquid mixture, as
will be described in more detail later herein.
[0026] In an embodiment, the marked fuel composition can comprise a
fuel. Generally, a fuel is a material or substance that stores
potential energy that can be released as useful energy (e.g., heat
or thermal energy, mechanical energy, kinetic energy, etc.) when
the material undergoes a chemical reaction (e.g., combustion).
[0027] In an embodiment, the fuel comprises a naturally-occurring
material. Alternatively, the fuel comprises a synthetic material.
Alternatively, the fuel comprises a mixture of a
naturally-occurring and a synthetic material. Nonlimiting examples
of fuels suitable for use in the present disclosure include
gasoline, diesel, jet fuel, kerosene, non-petroleum derived fuels,
alcohol fuels, ethanol, methanol, propanol, butanol, biodiesel,
maritime fuels, and the like, or combinations thereof.
[0028] In an embodiment, the marked fuel composition can comprise a
fuel marker. In an embodiment, the fuel maker can comprise at least
one compound characterized by Formula I:
##STR00005##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.20
alkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.3 and
R.sup.3' can each independently be hydrogen or a C.sub.1 to C.sub.4
alkyl group; R.sup.4 and R.sup.4' can each independently be
hydrogen, a C.sub.1 to C.sub.4 alkyl group, a C.sub.4 to C.sub.10
cycloalkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.5 and
R.sup.5' can each independently be a C.sub.4 to C.sub.10 alkyl
group; R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.6 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group. The
compound characterized by Formula I can be further subjected to
GC-MS using electron ionization, wherein the compound characterized
by Formula I produces at least one ion having a mass-to-charge
ratio of from about 300 to about 600 at an ionization energy of
equal to or greater than about 70 eV, as will be described in more
detail later herein. In an embodiment, the marked fuel composition
can comprise at least two compounds characterized by Formula I.
[0029] In an embodiment of the compound characterized by Formula I,
X is O or S. In such an embodiment, R.sup.1 and R.sup.2 can be lone
non-bonding electron pairs. Generally, a lone non-bonding electron
pair is a pair of electrons (e.g., a valence set of two electrons)
that is not bonding or shared with another atom--as opposed to
bonding electron pairs that are shared between different atoms, as
they form bonds (e.g., covalent bonds) between such atoms.
[0030] In an embodiment of the compound characterized by Formula I,
X is O. In such an embodiment, the compound characterized by
Formula I can have Structure A:
##STR00006##
[0031] In an embodiment of the compound characterized by Formula I,
X is S. In such an embodiment, the compound characterized by
Formula I can have any of Structure B, Structure C, Structure D,
Structure E, or Structure F:
##STR00007##
[0032] In an embodiment of the compound characterized by Formula I,
X is C. In such an embodiment, R.sup.1 and R.sup.2 can each
independently be hydrogen, a C.sub.1 to C.sub.20 alkyl group, or a
C.sub.6 to C.sub.10 aryl group.
[0033] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be a C.sub.1
to C.sub.20 alkyl group, alternatively a C.sub.1 to C.sub.10 alkyl
group, alternatively a C.sub.1 to C.sub.7 alkyl group, or
alternatively a C.sub.1 to C.sub.4 alkyl group. As used herein, the
term "alkyl group" is a general term that refers to any univalent
group derived from an alkane by removal of a hydrogen atom from any
carbon atom of the alkane. Further, as used herein, the term "alkyl
groups" can refer to primary alkyl groups, secondary alkyl groups
(sec-alkyl groups), or tertiary alkyl groups (tert-alkyl groups or
t-alkyl groups). Alkanes are acyclic branched or unbranched
hydrocarbons having the general formula C.sub.nH.sub.2n+2 and
consist entirely of hydrogen atoms and saturated carbon atoms. For
purposes of the disclosure herein, the term "alkyl group" refers to
any alkyl group, including without limitation primary alkyl groups,
sec-alkyl groups, tert-alkyl groups, n-alkyl groups, iso-alkyl
groups, substituted alkyl groups, unsubstituted or non-substituted
alkyl groups, and the like, or combinations thereof. For example,
the term "butyl group" refers to a n-butyl group, an iso-butyl
group, a sec-butyl group, a tert-butyl group, or combinations
thereof. Generally, a "substituted organic group" (e.g.,
substituted alkyl group, substituted cycloalkyl group, substituted
aryl group, etc.) refers to an organic group wherein a hydrogen
atom has been substituted with an atom or group of atoms, e.g., a
substituent. For purposes of the disclosure herein, a C.sub.x to
C.sub.y organic group (e.g., an alkyl group, a cycloalkyl group, an
aryl group, etc.) includes groups represented by all integers
between x and y, including x and y. For example, a C.sub.1 to
C.sub.10 organic group includes C.sub.1, C.sub.2, C.sub.3, C.sub.4,
C.sub.5, C.sub.6, C.sub.7, C.sub.8, C.sub.9, and C.sub.10 organic
groups. Further, for example, a C.sub.6 to C.sub.12 organic group
includes C.sub.6, C.sub.7, C.sub.8, C.sub.9, C.sub.10, C.sub.11 and
C.sub.12 organic groups.
[0034] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be selected
from the group consisting of a methyl group, an ethyl group, a
n-propyl group, an iso-propyl group, a n-butyl group, an iso-butyl
group, a sec-butyl group, a tert-butyl group, a pentyl group, a
n-pentyl group, an iso-pentyl group, a sec-pentyl group, a hexyl
group, a heptyl group, an octyl group, a nonyl group, a decyl
group, a undecyl group, a dodecyl group, a tridecyl group, a
tetradecyl group, a pentadecyl group, a hexadecyl group, a
heptadecyl group, an octadecyl group and a nonadecyl group.
[0035] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be selected
from the group consisting of a methyl group, an ethyl group, a
n-propyl group, an iso-propyl group, a n-butyl group, an iso-butyl
group, a sec-butyl group, a tert-butyl group and a heptyl
group.
[0036] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each be a methyl group.
[0037] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be a C.sub.6
to C.sub.10 aryl group, alternatively a C.sub.6 to C.sub.8 aryl
group, alternatively a C.sub.6 aryl group, alternatively a C.sub.7
aryl group, or alternatively a C.sub.8 aryl group. As used herein,
the term "aryl group" is a general term that refers to any aromatic
group derived from an arene by removal of a hydrogen atom from any
carbon atom of an aromatic ring. Generally, arenes (or aromatic
hydrocarbons) are hydrocarbons with alternating double bonds and
single bonds between carbon atoms, wherein the carbon atoms form
rings, and can be monocyclic arenes (e.g., benzene, toluene,
o-xylene, m-xylene, p-xylene, biphenyl, diphenylmethane, etc.),
which can contain one or more aromatic rings, wherein the rings are
not fused to each other; or polycyclic arenes (e.g., naphthalene,
anthracene, etc.), which can contain two or more aromatic rings,
wherein at least two of the rings are fused to each other. Except
for phenyl, which is derived by removal of a hydrogen atom from a
carbon atom of a benzene ring, all other aryl groups are position
dependent, with respect to the already existing substituents on the
aromatic ring from which the hydrogen is removed to create such
aryl group. For example, a tolyl group can be obtained by removing
one hydrogen atom from a carbon atom of the aromatic ring of
toluene, wherein such tolyl group can be o-tolyl, m-tolyl, or
p-tolyl, based on whether the hydrogen was removed from a carbon
that was positioned in ortho, metha, or para, respectively, with
respect to the methyl group. For purposes of the disclosure herein,
the term "aryl group" refers to any aryl group, including without
limitation any isomers, such as ortho, meta, para isomers, a
substituted aryl group, a unsubstituted aryl group, and the like,
or combinations thereof. For example, the term "tolyl group" refers
to o-tolyl group, m-tolyl group, p-tolyl group, or combinations
thereof.
[0038] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be hydrogen,
a C.sub.1 to C.sub.10 alkyl group, or a C.sub.6 to C.sub.10 aryl
group, wherein the C.sub.6 to C.sub.10 aryl group can comprise a
phenyl group, a substituted phenyl group, a tolyl group, a
substituted tolyl group, a xylyl group, or a substituted xylyl
group.
[0039] In an embodiment of the compound characterized by Formula I,
X is C. In such an embodiment, the compound characterized by
Formula I can have any of Structures G-O:
##STR00008## ##STR00009##
[0040] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be a C.sub.1
to C.sub.4 alkyl group, or a C.sub.6 to C.sub.10 aryl group;
wherein the C.sub.6 to C.sub.10 aryl group can comprise a phenyl
group, a substituted phenyl group, a tolyl group, a substituted
tolyl group, a xylyl group, or a substituted xylyl group.
[0041] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be selected
from the group consisting of a methyl group, an ethyl group, a
n-propyl group, an iso-propyl group, a n-butyl group, an iso-butyl
group, a sec-butyl group, a tert-butyl group, a pentyl group, a
n-pentyl group, an iso-pentyl group, a sec-pentyl group, a hexyl
group, a heptyl group, an octyl group, a nonyl group, a decyl
group, a undecyl group, a dodecyl group, a tridecyl group, a
tetradecyl group, a pentadecyl group, a hexadecyl group, a
heptadecyl group, an octadecyl group and a nonadecyl group. In such
an embodiment, the compound characterized by Formula I can have any
of Structure G, Structure H, Structure I, Structure J, Structure K,
Structure L, Structure M, Structure N, or Structure O.
[0042] In an embodiment of the compound characterized by Formula I,
X is C. In such an embodiment, the compound characterized by
Formula I can have Structure P:
##STR00010##
[0043] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be a methyl
group or a phenyl group. In such an embodiment, the compound
characterized by Formula I can have Structure P.
[0044] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be hydrogen,
a C.sub.1 to C.sub.10 alkyl group, or a C.sub.6 to C.sub.10 aryl
group.
[0045] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.1 and R.sup.2 can each independently be a C.sub.1
to C.sub.10 alkyl group, or a C.sub.6 to C.sub.10 aryl group. In
such an embodiment, the compound characterized by Formula I can
have Structure P.
[0046] In an embodiment, R.sup.3 and R.sup.3' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group, such
as for example a methyl group, an ethyl group, a n-propyl group, an
iso-propyl group, a n-butyl group, an iso-butyl group, a sec-butyl
group, or a tert-butyl group.
[0047] In an embodiment, R.sup.3 and R.sup.3' can each
independently be hydrogen or a methyl group.
[0048] In an embodiment of the compound characterized by Formula I,
X is O, and R.sup.3 and R.sup.3' can each be hydrogen. In such an
embodiment, the compound characterized by Formula I can have
Structure A.
[0049] In another embodiment of the compound characterized by
Formula I, X is S, and R.sup.3 and R.sup.3' can each be hydrogen.
In such an embodiment, the compound characterized by Formula I can
have any of Structure B, Structure C, or Structure D.
[0050] In yet another embodiment of the compound characterized by
Formula I, X is C, and R.sup.3 and R.sup.3' can each be hydrogen.
In such an embodiment, the compound characterized by Formula I can
have any of Structure G, Structure H, Structure I, Structure J,
Structure L, Structure M, Structure N, Structure O, or Structure
P.
[0051] In still yet another embodiment of the compound
characterized by Formula I, X is S, and R.sup.3 and R.sup.3' can
each be a methyl group. In such an embodiment, the compound
characterized by Formula I can have Structure E.
[0052] In still yet another embodiment of the compound
characterized by Formula I, X is S, and R.sup.3 and R.sup.3' can
each independently be hydrogen or a methyl group. In such an
embodiment, the compound characterized by Formula I can have
Structure F.
[0053] In still yet another embodiment of the compound
characterized by Formula I, X is C, and R.sup.3 and R.sup.3' can
each be a methyl group. In such an embodiment, the compound
characterized by Formula I can have Structure K.
[0054] In an embodiment, R.sup.4 and R.sup.4' can each
independently be hydrogen, a C.sub.1 to C.sub.4 alkyl group, a
C.sub.4 to C.sub.10 cycloalkyl group, or a C.sub.6 to C.sub.10 aryl
group. As used herein, the term "cycloalkyl group" is a general
term that refers to any univalent group derived from a cycloalkane
by removal of a hydrogen atom from any carbon atom of the
cycloalkane ring. Cycloalkanes are saturated monocyclic
hydrocarbons, and can be with or without side chains. Cycloalkanes
and their corresponding cycloalkyl groups can also be substituted
or unsubstituted. Whether the cycloalkyl is substituted or
unsubstituted, the nomenclature of the cycloalkyl refers to the
number of carbon atoms present in the cycloalkane ring. For
example, a cyclobutyl group has 4 carbon atoms in the cycloalkyl
ring; and a methylcyclopropyl group has 3 carbon atoms in the
cycloalkyl ring, but a total of 4 carbon atoms.
[0055] In an embodiment of the compound characterized by Formula I,
X is O, and R.sup.4 and R.sup.4' can each be hydrogen. In such an
embodiment, the compound characterized by Formula I can have
Structure A.
[0056] In another embodiment of the compound characterized by
Formula I, X is S, and R.sup.4 and R.sup.4' can each be hydrogen.
In such an embodiment, the compound characterized by Formula I can
have any of Structure B, or Structure E.
[0057] In yet another embodiment of the compound characterized by
Formula I, X is S, and R.sup.4 and R.sup.4' can each independently
be hydrogen or a tert-butyl group. In such an embodiment, the
compound characterized by Formula I can have Structure F.
[0058] In still yet another embodiment of the compound
characterized by Formula I, X is C, and R.sup.4 and R.sup.4' can
each be hydrogen. In such an embodiment, the compound characterized
by Formula I can have any of Structure I, Structure J, Structure K,
Structure M, Structure O, or Structure P.
[0059] In an embodiment, R.sup.4 and R.sup.4' can each
independently be a C.sub.1 to C.sub.4 alkyl group, such as for
example a methyl group, an ethyl group, a n-propyl group, an
iso-propyl group, a n-butyl group, an iso-butyl group, a sec-butyl
group, or a tert-butyl group.
[0060] In an embodiment of the compound characterized by Formula I,
X is S, and R.sup.4 and R.sup.4' can each be a methyl group. In
such an embodiment, the compound characterized by Formula I can
have any of Structure C, or Structure D.
[0061] In another embodiment of the compound characterized by
Formula I, X is C, and R.sup.4 and R.sup.4' can each be a methyl
group. In such an embodiment, the compound characterized by Formula
I can have any of Structure H, or Structure N.
[0062] In an embodiment, R.sup.4 and R.sup.4' can each
independently be a C.sub.4 to C.sub.10 cycloalkyl group, such as
for example a cyclobutyl group, a substituted cyclobutyl group, a
cyclopentyl group, a substituted cyclopentyl group, a cyclohexyl
group, a substituted cyclohexyl group, a cycloheptyl group, a
substituted cycloheptyl group, a cyclooctyl group, or a substituted
cyclooctyl group. In such an embodiment, the C.sub.4 to C.sub.10
cycloalkyl group can comprise a cyclohexyl group.
[0063] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.4 and R.sup.4' can each be a cyclohexyl group. In
such an embodiment, the compound characterized by Formula I can
have Structure L.
[0064] In an embodiment, R.sup.4 and R.sup.4' can each
independently be a C.sub.6 to C.sub.10 aryl group, such as for
example a phenyl group, a substituted phenyl group, a tolyl group,
a substituted tolyl group, a xylyl group, or a substituted xylyl
group.
[0065] In an embodiment of the compound characterized by Formula I,
X is C, and R.sup.4 and R.sup.4' can each be a phenyl group. In
such an embodiment, the compound characterized by Formula I can
have Structure G.
[0066] In an embodiment, R.sup.5 and R.sup.5' can each
independently be a C.sub.4 to C.sub.10 alkyl group, such as for
example a n-butyl group, an iso-butyl group, a sec-butyl group, a
tert-butyl group, a pentyl group, a n-pentyl group, an iso-pentyl
group, a sec-pentyl group, a hexyl group, a heptyl group, an octyl
group, a nonyl group, or a decyl group.
[0067] In an embodiment, R.sup.5 and R.sup.5' can both be a pentyl
group or a heptyl group.
[0068] In an embodiment of the compound characterized by Formula I,
X is S, and R.sup.5 and R.sup.5' can each be a pentyl group. In
such an embodiment, the compound characterized by Formula I can
have any of Structure D, Structure E, or Structure F.
[0069] In another embodiment of the compound characterized by
Formula I, X is C, and R.sup.5 and R.sup.5' can each be a pentyl
group. In such an embodiment, the compound characterized by Formula
I can have any of Structure G, Structure K, or Structure L.
[0070] In yet another embodiment of the compound characterized by
Formula I, X is O, and R.sup.5 and R.sup.5' can each be a heptyl
group. In such an embodiment, the compound characterized by Formula
I can have Structure A.
[0071] In still yet another embodiment of the compound
characterized by Formula I, X is S, and R.sup.5 and R.sup.5' can
each be a heptyl group. In such an embodiment, the compound
characterized by Formula I can have any of Structure B, or
Structure C.
[0072] In still yet another embodiment of the compound
characterized by Formula I, X is C, and R.sup.5 and R.sup.5' can
each be a heptyl group. In such an embodiment, the compound
characterized by Formula I can have any of Structure H, Structure
I, Structure J, Structure M, Structure N, Structure O, or Structure
P.
[0073] In an embodiment of the compound characterized by Formula I,
X is C; R.sup.1 and R.sup.2 can each be hydrogen; and R.sup.5 and
R.sup.5' can both be a C.sub.4 to C.sub.10 alkyl group, such as for
example a pentyl group or a heptyl group.
[0074] In an embodiment of the compound characterized by Formula I,
X is C; R.sup.1 and R.sup.2 can each be hydrogen; and R.sup.5 and
R.sup.5' can each be a pentyl group. In another embodiment of the
compound characterized by Formula I, X is C; R.sup.1 and R.sup.2
can each be hydrogen; and R.sup.5 and R.sup.5' can each be a heptyl
group.
[0075] In an embodiment of the compound characterized by Formula I,
X is C; R.sup.1 and R.sup.2 can each be a methyl group; and R.sup.5
and R.sup.5' can both be a C.sub.4 to C.sub.10 alkyl group, such as
for example a pentyl group or a heptyl group.
[0076] In an embodiment of the compound characterized by Formula I,
X is C; R.sup.1 and R.sup.2 can each be a methyl group; and R.sup.5
and R.sup.5' can each be a pentyl group. In such an embodiment, the
compound characterized by Formula I can have any of Structure G, or
Structure L.
[0077] In another embodiment of the compound characterized by
Formula I, X is C; R.sup.1 and R.sup.2 can each be a methyl group;
and R.sup.5 and R.sup.5' can each be a heptyl group. In such an
embodiment, the compound characterized by Formula I can have any of
Structure H, Structure J, or Structure N.
[0078] In an embodiment, R.sup.4, R.sup.4', R.sup.5, and R.sup.5'
can each independently be a C.sub.1 to C.sub.10 alkyl group, a
C.sub.4 to C.sub.10 cycloalkyl group, or a C.sub.6 to C.sub.10 aryl
group, wherein the C.sub.4 to C.sub.10 cycloalkyl group can
comprise a cyclobutyl group, a substituted cyclobutyl group, a
cyclopentyl group, a substituted cyclopentyl group, a cyclohexyl
group, a substituted cyclohexyl group, a cycloheptyl group, a
substituted cycloheptyl group, a cyclooctyl group, or a substituted
cyclooctyl group. In such an embodiment, the C.sub.4 to C.sub.10
cycloalkyl group can comprise a cyclohexyl group, such as for
example in Structure L.
[0079] In an embodiment, R.sup.6 and R.sup.6' can each
independently be hydrogen or a C.sub.1 to C.sub.6 alkyl group, such
as for example a methyl group, an ethyl group, a n-propyl group, an
iso-propyl group, a n-butyl group, an iso-butyl group, a sec-butyl
group, a tert-butyl group, a pentyl group, a n-pentyl group, an
iso-pentyl group, a sec-pentyl group, or a hexyl group.
[0080] In an embodiment, R.sup.6 and R.sup.6' can each
independently be selected from the group consisting of a methyl
group, an ethyl group, a n-propyl group, an iso-propyl group, a
n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl
group, a pentyl group, a n-pentyl group, an iso-pentyl group, a
sec-pentyl group and a hexyl group.
[0081] In an embodiment of the compound characterized by Formula I,
X is O, and R.sup.6 and R.sup.6' can each be hydrogen. In such an
embodiment, the compound characterized by Formula I can have
Structure A.
[0082] In another embodiment of the compound characterized by
Formula I, X is S, and R.sup.6 and R.sup.6' can each be hydrogen.
In such an embodiment, the compound characterized by Formula I can
have any of Structure B, or Structure C.
[0083] In yet another embodiment of the compound characterized by
Formula I, X is S, and R.sup.6 and R.sup.6' can each be a
tert-butyl group. In such an embodiment, the compound characterized
by Formula I can have any of Structure D, or Structure E.
[0084] In still yet another embodiment of the compound
characterized by Formula I, X is S, and R.sup.6 and R.sup.6' can
each independently be hydrogen or a tert-butyl group. In such an
embodiment, the compound characterized by Formula I can have
Structure F.
[0085] In still yet another embodiment of the compound
characterized by Formula I, X is C, and R.sup.6 and R.sup.6' can
each be hydrogen. In such an embodiment, the compound characterized
by Formula I can have any of Structure G, Structure I, Structure L,
Structure M, Structure N, Structure O, or Structure P.
[0086] In still yet another embodiment of the compound
characterized by Formula I, X is C, and R.sup.6 and R.sup.6' can
each be methyl. In such an embodiment, the compound characterized
by Formula I can have Structure H.
[0087] In still yet another embodiment of the compound
characterized by Formula I, X is C, and R.sup.6 and R.sup.6' can
each be iso-propyl. In such an embodiment, the compound
characterized by Formula I can have Structure J.
[0088] In still yet another embodiment of the compound
characterized by Formula I, X is C, and R.sup.6 and R.sup.6' can
each be a tert-butyl group. In such an embodiment, the compound
characterized by Formula I can have Structure K.
[0089] In an embodiment, R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group, such
as for example a methyl group, an ethyl group, a n-propyl group, an
iso-propyl group, a n-butyl group, an iso-butyl group, a sec-butyl
group, or a tert-butyl group.
[0090] In an embodiment, R.sup.7 and R.sup.7' can each
independently be hydrogen or a methyl group.
[0091] In an embodiment of the compound characterized by Formula I,
X is O, and R.sup.7 and R.sup.7' can each be hydrogen. In such an
embodiment, the compound characterized by Formula I can have
Structure A.
[0092] In another embodiment of the compound characterized by
Formula I, X is S, and R.sup.7 and R.sup.7' can each be hydrogen.
In such an embodiment, the compound characterized by Formula I can
have any of Structure B, Structure C, Structure D, or Structure
E.
[0093] In yet another embodiment of the compound characterized by
Formula I, X is S, and R.sup.7 and R.sup.7' can each independently
be hydrogen or a methyl group. In such an embodiment, the compound
characterized by Formula I can have Structure F.
[0094] In still yet another embodiment of the compound
characterized by Formula I, X is C, and R.sup.7 and R.sup.7' can
each be hydrogen. In such an embodiment, the compound characterized
by Formula I can have any of Structure G, Structure H, Structure I,
Structure J, Structure K, Structure L, Structure M, Structure N,
Structure O, or Structure P.
[0095] In an embodiment, the compound characterized by Formula I
can be produced by reaction of an intermediate phenol (AAA) with an
alkylating agent R.sup.5X to yield Formula I according to the
following reaction:
##STR00011##
[0096] Other alkylating agents, such as alcohol derivatives
(mesylates, tosylates, etc.) can be employed. Intermediate phenols
AAA can be made by any suitable methodology. One example where X is
C includes the reaction of a ketone with the appropriate phenol
(BBB), according to the following reaction scheme:
##STR00012##
Subsequent alkylation as described leads to compounds of Formula
I.
[0097] In an embodiment, a fuel marker comprising a compound
characterized by Formula I as disclosed herein can be resistant to
laundering. Generally, "laundering" of a fuel refers to processing
or treating the fuel with laundering agents to partially or
completely remove or mask the fuel marker such that the fuel cannot
be properly authenticated. For purposes of the disclosure herein,
the term "laundering agent" refers to any material or substance
which is capable of partially or completely removing a fuel marker
from a marked fuel composition.
[0098] Nonlimiting examples of laundering agents include strong
acids, alkalis, absorbent materials, clay, carbon, active carbon,
charcoal, active charcoal, paper filter, straw, microfilters,
silica, silica gel, molecular sieves, adsorbent materials, and the
like, or combinations thereof.
[0099] In an embodiment, the fuel marker can be present within the
marked fuel composition in an amount of from about 1 ppb to about
50 ppm, alternatively from about 10 ppb to about 25 ppm,
alternatively from about 100 ppb to about 10 ppm, alternatively
from about 250 ppb to about 5 ppm, or alternatively from about 500
ppb to about 1 ppm, based on the total weight of the marked fuel
composition.
[0100] In an embodiment, the marked fuel composition can be
contacted with a heavy compound to yield a marked fuel mixture,
wherein the heavy compound comprises a compound of Formula I having
at least one atom replaced with an isotope tag (e.g., a heavy
compound of Formula I). In such an embodiment, the heavy compound
can be contacted in a known amount with the marked fuel
composition, as will be disclosed in more detail later herein.
Generally, an isotope tag refers to an atom that replaced in a
molecule (e.g., a molecule of a compound of Formula I) another atom
of the same element that has a different number of neutrons when
compared to the atom that replaced it. For purposes of the
disclosure herein, a fuel composition comprising a heavy compound
will be referred to as a "marked fuel mixture," or simply "marked
fuel composition."
[0101] Nonlimiting examples of isotope tags suitable for use in the
present disclosure include deuterium (.sup.2H), carbon-13
(.sup.13C), oxygen-17 (.sup.17O), sulfur-34 (.sup.34S), and the
like, or combinations thereof. For example, a commercially
available phenol-.sup.2H.sub.6 (e.g., deuterated phenol d-BBB) can
be reacted with ketones to create various deuterated bisphenol
derivatives (e.g., d-AAA) according to the following reaction
scheme:
##STR00013##
Subsequent alkylation yields the desired heavy compounds (e.g.,
deuterated compound of Formula I, d-Formula I). Performing the same
synthesis with a commercially available .sup.13C.sub.6 labelled
phenol would yield the .sup.13C heavy compound. One skilled in the
art would recognize that other isotopically labelled intermediates
could be used to synthesize a variety of heavy compounds of various
isotopic substitution.
[0102] In an embodiment, the marked fuel mixture comprises a heavy
compound of Formula I, wherein the isotope tag comprises deuterium
(.sup.2H). In such an embodiment, the heavy compound of Formula I
can further comprise other isotope tags, such as for example
carbon-13 (.sup.13C), oxygen-17 (.sup.17O), sulfur-34 (.sup.34S),
and the like, or combinations thereof.
[0103] In an embodiment, the marked fuel mixture comprises a heavy
compound of Formula I, wherein the isotope tag comprises carbon-13
(.sup.13C). In such an embodiment, the heavy compound of Formula I
can further comprise other isotope tags, such as for example
deuterium (.sup.2H), oxygen-17 (.sup.17O), sulfur-34 (.sup.34S),
and the like, or combinations thereof.
[0104] In an embodiment, the marked fuel mixture comprises a heavy
compound of Formula I, wherein the isotope tag comprises oxygen-17
(.sup.17O). In such an embodiment, the heavy compound of Formula I
can further comprise other isotope tags, such as for example
deuterium (.sup.2H), carbon-13 (.sup.13C), sulfur-34 (.sup.34S),
and the like, or combinations thereof.
[0105] In an embodiment, the marked fuel mixture comprises a heavy
compound of Formula I, wherein X can be O, wherein X comprises the
isotope tag, and wherein the isotope tag comprises oxygen-17
(.sup.17O). In such an embodiment, the heavy compound of Formula I
can further comprise other isotope tags, such as for example
deuterium (.sup.2H), carbon-13 (.sup.13C), sulfur-34 (.sup.34S),
and the like, or combinations thereof.
[0106] In an embodiment, the marked fuel mixture comprises a heavy
compound of Formula I, wherein X can be S, and wherein the isotope
tag comprises sulfur-34 (.sup.34S). In such an embodiment, the
heavy compound of Formula I can further comprise other isotope
tags, such as for example deuterium (.sup.2H), carbon-13
(.sup.13C), oxygen-17 (.sup.17O), and the like, or combinations
thereof.
[0107] In an embodiment, the isotope tag can be introduced into the
compound of Formula I to form a heavy compound by using any
suitable methodology. In an embodiment, the isotope tag can be
introduced into the compound of Formula I by chemical isotope
exchange (i.e., exchange of isotopes between different types of
molecules or ions in the course of a chemical reaction).
[0108] In some embodiments, the isotope tag can be introduced into
the compound of Formula I by subjecting the compound of Formula I
to a chemical isotope exchange with at least one isotope tag
compound. Generally, an isotope tag compound refers to any compound
containing an isotope tag (e.g., deuterium (.sup.2H), carbon-13
(.sup.13C), oxygen-17 (.sup.17O), sulfur-34 (.sup.34S), etc.),
where such isotope tag compound can participate in a chemical
isotope exchange reaction and/or a reaction for transferring the
isotope tag to another compound.
[0109] In other embodiments, the isotope tag can be introduced into
the compound of Formula I by subjecting a precursor of the compound
of Formula I to a chemical isotope exchange with at least one
isotope tag compound. For example, during the synthesis of the
compound of Formula I, a precursor of the compound of Formula I can
be subjected to a chemical isotope exchange with at least one
isotope tag compound.
[0110] In yet other embodiments, the isotope tag can be introduced
into the compound of Formula I by subjecting a first precursor of
the compound of Formula I to a reaction with at least one isotope
tag compound to yield a second precursor of the compound of Formula
I, wherein the second precursor of the compound of Formula I
comprises an isotope tag. In such embodiments, the second precursor
of the compound of Formula I can be further converted to yield a
heavy compound of Formula I, wherein the heavy compound of Formula
I comprises an isotope tag.
[0111] In still yet other embodiments, the isotope tag can be
introduced into the compound of Formula I by subjecting a precursor
of the compound of Formula I to a reaction with at least one
isotope tag compound to yield a heavy compound of Formula I,
wherein the heavy compound of Formula I comprises an isotope tag.
In an embodiment, the isotope tag can be located at any position in
the structure, alternatively the structure comprises isotope tags
at multiple positions. In an embodiment, the position for isotopic
substitution can be chosen to lead to a significant shift in the
mass-to-charge ratio (m/z) of the heavy compound. For example, the
position for isotopic substitution can be chosen to provide a m/z
shift of from about 4 atomic mass units (AMU) to about 12 AMU,
alternatively greater than about 4 AMU, alternatively greater than
about 8 AMU, or alternatively greater than about 12 AMU.
[0112] In some embodiments, a precursor of the compound of Formula
I (e.g., a first precursor of the compound of Formula I, a second
precursor of the compound of Formula I, etc.) can comprise an
isotope tag compound, such as for example deuterated 1-bromopentane
(1-bromopentane-d.sub.11, C.sub.5D.sub.11Br), deuterated
1-bromoheptane (1-bromoheptane-d.sub.15, C.sub.7D.sub.15Br),
deuterated phenol (C.sub.6D.sub.5OD), and the like, or combinations
thereof.
[0113] Nonlimiting examples of isotope tag compounds suitable for
use in the present disclosure include deuterated 1-bromopentane
(1-bromopentane-d.sub.11, C.sub.5D.sub.11Br), deuterated
1-bromoheptane (1-bromoheptane-d.sub.15, C.sub.7D.sub.15Br),
deuterated phenol (C.sub.6D.sub.5OD), deuterated water (deuterium
oxide, D.sub.2O), deuterated hydrochloric acid (DCl), deuterated
acetic acid (CD.sub.3COOD), deuterated acetone
(CD.sub.3COCD.sub.3), deuterated methanol (CD.sub.3OD), deuterated
acetonitrile (CD.sub.3CN), deuterated benzene (C.sub.6D.sub.6),
deuterated chloroform (CDCl.sub.3), deuterated cyclohexane
(C.sub.6D.sub.12), deuterated N,N-dimethylformamide
(DCON(CD.sub.3).sub.2), deuterated dimethyl sulphoxide
(CD.sub.3SOCD.sub.3), deuterated ethanol (C.sub.2D.sub.5OD),
deuterated methylene chloride (CD.sub.2Cl.sub.2), deuterated
nitromethane (CD.sub.3NO.sub.2), deuterated pyridine
(C.sub.5D.sub.5N), deuterated tetrahydrofuran (C.sub.4D.sub.8O),
deuterated toulene (C.sub.6D.sub.5CD.sub.3), deuterated
trifluoroacetic acid (CF.sub.3COOD); acetaldehyde-1-.sup.13C,
acetaldehyde-1,2-.sup.13C.sub.2, acetic acid-1-.sup.13C, acetic
acid-2-.sup.13C, acetic acid-1,2-.sup.13C, acetic
anhydride-1,1-.sup.13C.sub.2, acetic anhydride-2,2-.sup.13C.sub.2,
acetic anhydride-1,1,2,2-.sup.13C.sub.4, acetone-2-.sup.13C,
acetone-1,3-.sup.13C.sub.2, acetone-1,2,3-.sup.13C.sub.3,
acetonitrile-1-.sup.13C, acetonitrile-2-.sup.13C,
acetonitrile-1,2-.sup.13C.sub.2, acetophenone-1-.sup.13C,
acetophenone-2-.sup.13C, acetyl chloride-1-.sup.13C, acetyl
chloride-2-.sup.13C, acetyl chloride-1,2-.sup.13C.sub.2,
aniline-.sup.13C.sub.6, aniline chloride-.sup.13C.sub.6, aniline
sulfate-.sup.13C.sub.6, benzaldehyde-carbonyl-.sup.13C,
benzene-.sup.13C.sub.6, benzenesulfonyl chloride-.sup.13C.sub.6,
benzoic acid-carbonyl-.sup.13C, benzophenone-.sup.13C (carbonyl
labeled), benzophenone-.sup.13C.sub.12 (ring labeled), benzoyl
chloride-.sup.13C (ring labeled), benzoyl
chloride-carbonyl-.sup.13C, benzyl alcohol-.sup.13C.sub.6 (ring
labeled), tert-butyl chloride-.sup.13C, carbon dioxide-.sup.13C,
carbon disulfide-.sup.13C, carbon monoxide-.sup.13C, carbon
tetrachloride-.sup.13C, chloroacetic acid-1-.sup.13C, chloroacetic
acid-2-.sup.13C, chloroacetic acid-1,2-.sup.13C.sub.2,
chlorobenzene-.sup.13C.sub.6, chloroethane-1,2-.sup.13C.sub.2,
chloroform-.sup.13C, chloromethane-.sup.13C, cyanoacetic
acid-1-.sup.13C, cyanoacetic acid-2-.sup.13C, cyanoacetic
acid-.sup.13C (cyanide labeled), dichloromethane-.sup.13C, dimethyl
formamide-carbonyl-.sup.13C, dimethyl-.sup.13C.sub.2 sulfoxide,
ethyl acetate-1-.sup.13C, ethyl acetate-2-.sup.13C, ethyl
alcohol-1-.sup.13C, ethyl alcohol-2-.sup.13C, ethyl
alcohol-1,2-.sup.13C.sub.2, ethylamine-1-.sup.13C, ethyl
chloride-1,2-.sup.13C.sub.2, ethylene oxide-1,2-.sup.13C.sub.2,
formaldehyde-.sup.13C, formamide-.sup.13C, hexane-1-.sup.13C,
1,6-hexanediamine-1,6-.sup.13C.sub.2, isobutane-2-.sup.13C,
isopropanol-2-.sup.13C, methane-.sup.13C, methyl alcohol-.sup.13C,
methylamine-.sup.13C, methyl bromide-.sup.13C, methyl
chloride-.sup.13C, methylene chloride-.sup.13C, methyl
formate-.sup.13C, nitrobenzene-.sup.13C.sub.6,
nitromethane-.sup.13C, phosgene-.sup.13C, propane-2-.sup.13C,
1,3-propanediol-2-.sup.13C, propene-1-.sup.13C, propene-2-.sup.13C,
propene-3-.sup.13C, sodium acetate-1-.sup.13C, sodium
acetate-2-.sup.13C, sodium acetate-1,2-.sup.13C.sub.2, sodium
bicarbonate-.sup.13C, sodium carbonate-.sup.13C, sodium
cyanide-.sup.13C, sodium formate-.sup.13C, sodium
thiocyanate-.sup.13C, thiourea-.sup.13C, toluene-7-.sup.13C,
trichloroacetic acid-1,2-.sup.13C.sub.20, urea-.sup.13C;
water-.sup.17O, acetaldehyde-.sup.17O, adipic acid-.sup.17O.sub.4,
ammonium nitrate-.sup.17O.sub.3, benzophenone-.sup.17O, carbon
dioxide-.sup.17O.sub.2, carbon monoxide-.sup.17O, carbonyl
sulfide-.sup.17O, cyclopentanone-.sup.17O, deuterium
oxide-.sup.17O, dimethyl formamide-.sup.17O, ethanol-.sup.17O,
formic acid-.sup.17O, nitrous oxide-.sup.17O,
oxygen-.sup.17O.sub.2, phosgene-.sup.17O, urea-.sup.17O; carbon
disulfide-.sup.34S, carbonyl sulfide-.sup.34S, magnesium
sulfate-.sup.34S, potassium thiocyanate-.sup.34S, sulfur-.sup.34S,
sodium sulfate-.sup.34S, sulfur dioxide-.sup.34S, sulfuric
acid-.sup.34S, thioacetamide-.sup.34S, thioacetic acid-.sup.34S,
thiourea-.sup.34S; deuterated acetic acid-1-.sup.13C
(CD.sub.3CO.sub.2D), deuterated acetic acid-2-.sup.13C
(CD.sub.3CO.sub.2D), deuterated acetone-1,3-.sup.13C.sub.2
(CD.sub.3COCD.sub.3), deuterated acetone-1,2,3-.sup.12C.sub.3
(CD.sub.3COCD.sub.3), deuterated acetonitrile-1,2-.sup.12C
(CD.sub.3CN), deuterated acetonitrile-.sup.15N (CD.sub.3CN),
deuterated acetonitrile-1-.sup.13C (CD.sub.3CN), deuterated
ammonia-.sup.15N (ND.sub.3), deuterated ammonium chloride-.sup.15N
(ND.sub.4Cl), deuterated ammonium sulfate-.sup.15N.sub.2
((ND.sub.4).sub.2SO.sub.4), deuterated methane-.sup.13C
(CH.sub.3D), deuterated methane-.sup.13C (CD.sub.4), deuterated
methyl alcohol-.sup.13C (CD.sub.3OD), deuterated sodium
acetate-1-.sup.13C (CD.sub.3CO.sub.2Na), deuterated sodium
acetate-2-.sup.13C (CD.sub.3CO.sub.2Na), deuterated urea-.sup.13C
(ND.sub.2COND.sub.2), deuterated urea-.sup.13C,.sup.15N.sub.2
(ND.sub.2COND.sub.2); carbon dioxide-.sup.13C,.sup.17O;
cyanamide-.sup.13C,.sup.15N.sub.2; formamide-.sup.13C,.sup.15N;
thiourea-.sup.13C,.sup.15N.sub.2; urea-.sup.13C,.sup.15N.sub.2; and
the like, or combinations thereof.
[0114] In some embodiments, the isotope tag compounds can comprise
deuterated 1-bromopentane (1-bromopentane-d.sub.11,
C.sub.5D.sub.11Br). In other embodiments, the isotope tag compounds
can comprise deuterated 1-bromoheptane (1-bromoheptane-d.sub.15,
C.sub.7D.sub.15Br). In yet other embodiments, the isotope tag
compounds can comprise deuterated phenol (C.sub.6D.sub.5OD).
[0115] As will be appreciated by one of skill in the art, and with
the help of this disclosure, more than one isotope tag can be
introduced into a chemical compound, such as for example 2, 3, 4,
5, 6, 7, 8, 9, 10, or more isotope tags. In some embodiments, at
least two of the isotope tags of the compound of Formula I are the
same. In other embodiments, at least two of the isotope tags of the
compound of Formula I are different. In yet other embodiments, at
least two of the isotope tags of the compound of Formula I can be
the same, and/or at least two of the isotope tags of the compound
of Formula I can be different.
[0116] In an embodiment of a heavy compound of Formula I (e.g.,
deuterated compound of Formula I, d-Formula I), X is S. In such an
embodiment, the heavy compound of Formula I can have any of
deuterated Structure B (d-Structure B), or deuterated Structure F
(d-Structure F):
##STR00014##
[0117] In an embodiment, the heavy compound can be present within
the marked fuel mixture in an amount (e.g., can be added to a fuel
composition in a known amount) of from about 1 ppb to about 50 ppm,
alternatively from about 10 ppb to about 25 ppm, alternatively from
about 100 ppb to about 10 ppm, alternatively from about 250 ppb to
about 5 ppm, or alternatively from about 500 ppb to about 1 ppm,
based on the total weight of the marked fuel mixture.
[0118] In an embodiment, the marked fuel composition can be
prepared by using any suitable methodology. In an embodiment, a
method of forming a marked fuel composition can comprise contacting
(a) a fuel, and (b) a fuel marker comprising at least one compound
characterized by Formula I.
[0119] In some embodiments, the fuel marker comprising at least one
compound characterized by Formula I can be added to the fuel to
form the marked fuel composition. In other embodiments, the fuel
can be added to the fuel marker comprising at least one compound
characterized by Formula I to form the marked fuel composition.
[0120] In some embodiments, the fuel marker can be contacted with
the fuel in powder form. In other embodiments, the fuel marker can
be contacted with the fuel as a fuel marker solution, wherein the
fuel marker can be solubilized in one or more solvents to form a
fuel marker solution. In an embodiment, a solvent suitable for use
in the present disclosure is characterized by a flash point greater
than about 60.degree. C. and miscibility with the fuels disclosed
herein. Nonlimiting examples of solvents suitable for use in the
present disclosure for making a fuel marker solution include
hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons,
ethers, carbonates, esters, ketones, aldehydes, alcohols, nitriles,
and combinations thereof. Polar solvents which can be utilized
include without limitation water, ethers, carbonates, esters,
ketones, aldehydes, alcohols, nitriles, and mixtures thereof;
alternatively, ethers, carbonates, esters, ketones, aldehydes,
alcohols, nitriles, and mixtures thereof. Aprotic polar solvents
which can be utilized include without limitation ethers, esters,
ketones, aldehydes, nitriles, and mixtures thereof; alternatively,
ethers, nitriles, and mixtures thereof. Non-polar solvents include
without limitation hydrocarbons, aromatic hydrocarbons, halogenated
hydrocarbons, or mixtures thereof; alternatively, a hydrocarbon;
alternatively, an aromatic hydrocarbon; or alternatively, a
halogenated hydrocarbon. In another embodiment, the solvent
comprises aromatic solvent 150 and 200, N-methylpyrollidone,
2-ethylhexanol, hydrocarbon solvents such as mineral spirits, and
the like, or combinations thereof.
[0121] In an embodiment, an additive pack can comprise the fuel
marker. In such an embodiment, the additive pack comprises a fuel
marker solution. In an embodiment, the additive pack can further
comprise a detergent, a surfactant, a lubricant, an octane
enhancer, a crystallization inhibitor, a freeze point depressant,
and the like, or combinations thereof. In an embodiment, the
additive pack comprising the fuel marker can be contacted with the
fuel to form a marked fuel composition.
[0122] In embodiments where an additive pack is used, the fuel
marker comprising a compound characterized by Formula I can be
mixed with the additive pack prior to adding the additive pack to
the fuel. In an alternative embodiment, where the additive pack is
used, the fuel marker comprising the compound characterized by
Formula I and the additive pack can be added to the fuel at the
same time, without prior mixing of the fuel marker with the
additive pack. In other embodiments, where the additive pack is
used, the additive pack and the fuel marker comprising the compound
characterized by Formula I can be added to the fuel at different
times. For example, the additive pack can be added to the fuel
first, and the fuel marker comprising the compound characterized by
Formula I can be added to the fuel second. Further, for example,
the fuel marker comprising the compound characterized by Formula I
can be added to the fuel first, and the additive pack can be added
to the fuel second.
[0123] As will be appreciated by one of skill in the art, and with
the help of this disclosure, whether the fuel marker is contacted
with the fuel in powder form, as a fuel marker solution, or as part
of an additive pack, the concentration of the fuel marker in the
marked fuel composition can be known (e.g., calculated) based on
the amount of powder used, the concentration of the fuel marker in
the fuel marker solution or the additive pack, the amount of fuel
marker solution or additive pack used, etc.
[0124] In an embodiment, the fuel can be contained in a container,
a storage container, transport container, a tanker truck, tanker
ship, pipeline, or any other suitable means for transporting fuel
from one place to another.
[0125] In an embodiment, the fuel can be in a pipeline. For
example, the fuel could be transported through the pipeline from a
processing plant to a storage container. In such an embodiment, the
fuel marker can be injected through an injection valve into a fuel
stream travelling through the pipeline.
[0126] In an embodiment, the fuel can be in a transport container
(e.g., tanker truck, a tanker ship, etc.). In such an embodiment,
the fuel marker can be added to the transport container through a
port located on the transport container above the level of the fuel
in the container. Further, the fuel marker can be injected through
an injection valve into the transport container, wherein the
injection valve can be located below the level of the fuel in the
container.
[0127] In an embodiment, the storage container comprising the fuel
can be a static storage container (e.g., the storage container is
immobile, does not move or travel), wherein the static storage
container could be located above ground, below ground, or partially
below ground and partially above ground. In such an embodiment, the
fuel marker can be added to the static storage container through a
port located on the static storage container above the level of the
fuel in the container. Further, the fuel marker can be injected
through an injection valve into the static storage container,
wherein the injection valve can be located below the level of the
fuel in the container.
[0128] In an embodiment, the storage container comprising the fuel
can be a mobile storage container (e.g., the storage container is
mobile, it can move or travel). In such an embodiment, the fuel
marker can be added to the mobile storage container through a port
located on the mobile storage container above the level of the fuel
in the container. Further, the fuel marker can be injected through
an injection valve into the mobile storage container, wherein the
injection valve can be located below the level of the fuel in the
container.
[0129] In some embodiments, the fuel marker can be added to a dry
container (e.g., a container comprising no fuel). In such
embodiments, the fuel can be added to the container subsequent to
the addition of the fuel marker to the container.
[0130] In an embodiment, a method of determining (e.g., evaluating,
assessing, estimating, etc.) adulteration of a fuel can comprise
subjecting to an analytical technique a marked fuel composition
comprising a fuel and a fuel marker, wherein the fuel marker
comprises a compound characterized by Formula I.
[0131] In an embodiment, the analytical technique can comprise
GC-MS, nuclear magnetic resonance (NMR) spectroscopy, .sup.13C NMR
spectroscopy, surface enhanced Raman scattering spectroscopy, and
the like, or combinations thereof.
[0132] In an embodiment, a method of determining adulteration of a
fuel can comprise (i) acquiring a fuel sample; (ii) subjecting the
fuel sample to the analytical technique to determine fuel sample
data (e.g., marker concentration); and (iii) comparing the fuel
sample data to a target marking level (e.g., target marker
concentration; control data) used to mark the fuel. As will be
appreciated by one of skill in the art, and with the help of this
disclosure, the target marker concentration of the marked fuel
composition is generally acquired for marked fuel compositions at a
point where the fuel sample data is known, e.g., prior to any
possibility of adulteration. For example, acquisition of the target
marker concentration at the place of marking as quality standard
can provide for dosing of the marked fuels at the target marking
level.
[0133] In some embodiments, a method of determining adulteration of
a fuel can be performed without addition of standards to the fuel
sample. In an embodiment, a method of determining adulteration of a
fuel excludes the addition of standards to the fuel sample.
[0134] In other embodiments, a method of determining adulteration
of a fuel can require addition of a standard (e.g., internal
standard) to the fuel sample, such as for example a heavy compound,
as will be described in more detail later herein.
[0135] In an embodiment, if the fuel sample data (e.g., marker
concentration) matches the control data of the marked fuel
composition (e.g., target marker concentration), the fuel can be
deemed to be unadulterated fuel. As will be appreciated by one of
skill in the art, and with the help of this disclosure, the
"matching" of the fuel sample data (e.g., marker concentration)
with the control data of the marked fuel composition (e.g., target
marker concentration) has to be within experimental error limits
for the fuel sample to be deemed unadulterated, and such
experimental error limits are dependent on the particular
analytical technique used, the analytical instrumentation used for
the detection and analysis of the fuel marker, etc. The matching of
data could include measuring a marker concentration to determine if
the fuel has been diluted, by comparing the marker concentration
with the target marker concentration. The matching of data could
also include the detection of a marker that has been added to a
potential adulterant and should not be present in the fuel.
Quantification of the amount of such a marker would indicate the
extent of dilution by the potential adulterant.
[0136] In an embodiment, if the fuel sample data does not match the
control data of the marked fuel composition, the fuel can be deemed
to be adulterated fuel. As will be appreciated by one of skill in
the art, and with the help of this disclosure, the difference
between the fuel sample data and the control data of the marked
fuel composition has to fall outside of experimental error limits
(e.g., the fuel sample data and the control data of the marked fuel
composition do not match) for the sample to be deemed adulterated,
and such experimental error limits are dependent on the particular
analytical technique used, the analytical instrumentation used for
the detection and analysis of the fuel marker, etc. Methods for
matching and determination of the extent of adulteration of a
marked fuel, as well as methods for fuel authentication by using
more than one marker, are disclosed in greater detail in U.S. Pat.
No. 8,592,213, which is incorporated by reference herein in its
entirety.
[0137] In an embodiment, a method of determining adulteration of a
fuel can be performed in the field (e.g., on location, direct
detection, etc.). Determining adulteration of a fuel in the field
can include testing at any location where a fuel can be found.
Determining adulteration in the field can allow for rapid
qualitative and/or quantitative assessment of the presence and/or
amount of fuel marker in a fuel sample.
[0138] In another embodiment, a fuel sample can be collected from a
first location (e.g., a gas station), and then transported to a
second location (e.g., a laboratory) for further testing, e.g.,
determining adulteration.
[0139] In an embodiment, a method of determining adulteration of a
fuel can comprise contacting a marked fuel composition with a heavy
compound to yield a marked fuel mixture, wherein the heavy compound
comprises a compound of Formula I having at least one atom replaced
with an isotope tag. In such an embodiment, a known amount of the
heavy compound can be contacted with (e.g., added to) the marked
fuel composition to yield the marked fuel mixture (e.g., wherein
the heavy compound can be present in the marked fuel mixture in a
known amount). The heavy compound can be used as an internal
standard.
[0140] In an embodiment, the method of determining adulteration of
a fuel can further comprise subjecting the marked fuel mixture to
an analytical technique.
[0141] In an embodiment, the analytical technique can evaluate fuel
adulteration by (i) determining the presence of the heavy compound
in the marked fuel mixture; and (ii) determining a ratio of an
amount of the compound characterized by Formula I to the known
amount of the heavy compound in the marked fuel mixture.
[0142] In an embodiment, (i) determining the presence of the heavy
compound in the marked fuel mixture can further comprise
determining the presence of the compound characterized by Formula I
in the marked fuel mixture.
[0143] In an embodiment, (ii) determining a ratio of an amount of
the compound characterized by Formula I to a known amount of the
heavy compound in the marked fuel mixture further comprises
calculating the amount of the compound characterized by Formula I
in the marked fuel mixture.
[0144] As will be appreciated by one of skill in the art, and with
the help of this disclosure, the compound characterized by Formula
I and the heavy compound comprising a compound of Formula I having
at least one atom replaced with an isotope tag can have the same
chemical and physical properties, such as for example, melting
temperature, solubility, density, absorption, reactivity, chemical
stability, elution time, etc. Further, as will be appreciated by
one of skill in the art, and with the help of this disclosure, when
present in the same composition (e.g., marked fuel mixture), the
compound characterized by Formula I and the heavy compound
comprising a compound of Formula I having at least one atom
replaced with an isotope tag are challenging to separate from each
other by conventional analytical methods, such as chromatography,
and will be analyzed simultaneously, or nearly simultaneously by
the analytical technique.
[0145] In an embodiment, the compound characterized by Formula I
and the heavy compound comprising a compound of Formula I having at
least one atom replaced with an isotope tag can each display
analytical signals that are different (e.g., distinct, dissimilar,
etc.) from each other, thereby enabling simultaneous detection of
both the compound characterized by Formula I and the heavy
compound. As will be appreciated by one of skill in the art, and
with the help of this disclosure, isotope tags have unique
analytical signals and can be detected by a variety of analytical
techniques, and such unique analytical signals do not appear in the
absence of the isotope tag.
[0146] In an embodiment, the marked fuel mixture can be subjected
to the analytical technique to record an analytical signal for the
compound characterized by Formula I and an analytical signal for
the heavy compound in the marked fuel mixture. In such an
embodiment, the analytical signal for the compound characterized by
Formula I and the analytical signal for the heavy compound in the
marked fuel mixture can be different.
[0147] In some embodiments, the analytical signal for the compound
characterized by Formula I and the analytical signal for the heavy
compound in the marked fuel mixture can correlate (e.g., be
proportional, be directly proportional, etc.) with the amount of
the compound characterized by Formula I and the amount (e.g., known
amount) of the heavy compound in the marked fuel mixture,
respectively. In such embodiments, a ratio of the analytical signal
for the compound characterized by Formula I to the analytical
signal for the heavy compound in the marked fuel mixture can be the
same as (e.g., equal to) the ratio of the amount of the compound
characterized by Formula I to the known amount of the heavy
compound in the marked fuel mixture. The ratio of the amount of the
compound characterized by Formula I to the known amount of the
heavy compound in the marked fuel mixture can be used for
calculating the amount of the compound characterized by Formula I
in the marked fuel mixture based on the known amount of the heavy
compound in the marked fuel mixture. As will be appreciated by one
of skill in the art, and with the help of this disclosure, the
heavy compound is used as an internal standard for determining the
amount of the compound characterized by Formula I in the marked
fuel mixture. The internal standard is held fixed at a
predetermined concentration that will be used in the analysis and
the analyte (e.g., compound characterized by Formula I)
concentration is varied. The resulting data is used then to
generate a calibration curve that can be utilized in quantitating
the fuel sample data (e.g., fuel marker concentration).
[0148] The selection of an appropriate internal standard can be
very important in generating the most accurate results in this
particular type of analysis (e.g., fuel authentication using a
heavy compound as internal standard). For GC-MS analysis,
deuterated isotopologues can often be the best choice if available,
as they can very closely match a retention time of the fuel marker,
and can produce a signal on a different mass channel of a MS
detector, which would not interfere with integration of the fuel
marker signal. Alternatively, a structural isomer of a fuel marker
structure can be used to produce similar results, or a closely
related structure in the same or very similar chemical class can be
utilized. Without wishing to be limited by theory, the more
structurally similar the internal standard is to the fuel marker
structure, the more accurate the results will be.
[0149] In some embodiments, an internal standard can be
co-submitted or co-injected (e.g., via an automated liquid
injector) along with an unknown sample (e.g., fuel sample) for
analysis (e.g., GC-MS analysis). In other embodiments, an internal
standard solution can be mixed with an unknown solution (e.g., fuel
sample to be authenticated) to form a combined solution, and the
combined solution can be submitted or injected for analysis (e.g.,
GC-MS analysis). As will be appreciated by one of skill in the art,
and with the help of this disclosure, whether the internal standard
and the fuel sample are pre-mixed or co-injected, similar results
will be obtained from the GC-MS analysis.
[0150] In an embodiment, the method of determining adulteration of
a fuel can comprise determining an amount (e.g., concentration) of
a fuel marker (e.g., a compound characterized by Formula I) in the
fuel sample, based on the fuel sample data (e.g., analytical
signal).
[0151] In an embodiment, a method of determining adulteration of a
fuel can comprise (i) acquiring a fuel sample; (ii) adding a known
amount of the heavy compound to the fuel sample to yield a marked
fuel mixture; (iii) subjecting the marked fuel mixture to the
analytical technique to record an analytical signal for the
compound characterized by Formula I and an analytical signal for
the heavy compound; (iv) comparing the analytical signal for the
known amount of heavy compound to the analytical signal for the
compound characterized by Formula I; (v) determining a ratio of an
amount of the compound characterized by Formula I to the known
amount of the heavy compound in the marked fuel mixture; and (vi)
calculating the amount of the compound characterized by Formula I
in the marked fuel mixture. In such an embodiment, (i) acquiring a
fuel sample can further comprise determining the presence of the
compound characterized by Formula I in the fuel sample.
[0152] In an embodiment, the analytical technique can evaluate fuel
adulteration by determining the amount of the compound
characterized by Formula I in the marked fuel mixture, e.g., the
amount of the compound characterized by Formula I in the marked
fuel composition, the amount of the compound characterized by
Formula I in the fuel sample, etc.
[0153] In an embodiment, if the amount of the compound
characterized by Formula I in the fuel sample matches the control
data (e.g., target marker concentration) of the marked fuel
composition, the fuel can be deemed to be unadulterated fuel.
[0154] In an embodiment, if the amount of the compound
characterized by Formula I in the fuel sample does not match the
control data (e.g., target marker concentration) of the marked fuel
composition, the fuel can be deemed to be adulterated fuel.
[0155] In an embodiment, if a compound characterized by Formula I
is detected in an unmarked fuel, the fuel can be deemed to be
adulterated fuel.
[0156] In an embodiment, if a compound characterized by Formula I
is detected in a fuel marked with a marker other than the compound
characterized by Formula I, the resulting fuel can be deemed to be
adulterated fuel.
[0157] In an embodiment, a method of determining adulteration of a
fuel can comprise (i) acquiring a fuel sample; (ii) subjecting the
fuel sample to GC-MS to yield GC-MS data; and (iii) comparing the
GC-MS data of the fuel sample with the GC-MS data of the marked
fuel composition (e.g., control data of the marked fuel
composition). In such an embodiment, the method can further
comprise determining an amount of the compound characterized by
Formula I present in the marked fuel composition and/or the fuel
sample based on the GC-MS data.
[0158] GC-MS enables both qualitative and quantitative analysis of
mixtures of compounds. Generally, GC-MS is a combination of two
techniques into a single method of analysis for mixtures of
compounds (e.g., marked fuel composition, marked fuel mixture, fuel
sample, etc.). Gas chromatography (GC) is a very prevalent
technique for the separation of complex mixtures such as petroleum
products because of its high separation power and low limits of
detection when paired with a suitable detector like a mass
spectrometer. GC separates components of a mixture based on
differences in the chemical properties between different mixture
components and based on their relative affinities for a stationary
phase of a GC column. As a sample (e.g., fuel sample) travels along
the GC column, the mixture components separate (e.g., some
components will travel faster than others). The mixture components
will ideally exit the GC individually, and would enter the mass
spectrometer (MS) for further characterization. As will be
appreciated by one of skill in the art, and with the help of this
disclosure, sometimes certain mixture components will travel
together along the GC column, and will enter the MS together;
however, MS has the ability to discriminate between certain mixture
components that elute (come off) together from the GC column. The
different compounds can be retained by the GC column and then elute
from the GC column at different times (e.g., retention times), and
this can allow the MS downstream to analyze (e.g., capture, ionize,
accelerate, deflect, detect, etc.) individually the eluted
components. MS characterizes each component entering from the GC
individually by ionizing molecules (e.g., breaking each molecule
into ionized fragments) and detecting these fragments using their
mass-to-charge ratio. Nonlimiting examples of ionization methods
suitable for use in MS include electron ionization (also known as
electron impact), chemical ionization, electrospray ionization,
matrix-assisted laser desorption/ionization, inductively coupled
plasma, photoionization, glow discharge, field desorption, fast
atom bombardment, thermospray, spark ionization, thermal
ionization, and the like, or combinations thereof.
[0159] In an embodiment, the fuel sample and/or the marked fuel
mixture can be subjected to GC-MS, wherein the ionization method of
the MS comprises electron ionization.
[0160] Generally, MS allows identification of amount and type of
compounds (e.g., molecules) present in a sample by measuring the
mass-to-charge ratio and abundance of gas-phase ions. MS ionizes
chemical compounds to generate charged molecules or molecule
fragments and measures their mass-to-charge ratios. The molecule
fragments are actually charged ions with a certain mass. The mass
of the fragment divided by the charge is called the "mass-to-charge
ratio" (m/z). Since most fragments have a charge of +1, the
mass-to-charge ratio usually represents the molecular weight of the
fragment. MS produces a mass spectrum for each analyzed compound,
wherein the x-axis represents the mass-to-charge ratio and wherein
the y-axis represents the signal intensity (abundance) for each of
the fragments detected. As will be appreciated by one of skill in
the art, and with the help of this disclosure, the mass spectrum
produced by a given compound is essentially the same every time,
and can be regarded as a "fingerprint" for the compound. This
fingerprint can be used to identify the compound.
[0161] The y-axis in the mass spectrum can be a relative abundance
axis. The peak with the greatest abundance is usually referred to
as a "base peak," and for the purpose of making a relative
abundance axis the base peak intensity is set to 100%, such that
the entire mass spectrum is normalized to the base peak. In some
embodiments, the molecular ion peak can be the base peak. In such
embodiments, the entire mass spectrum can be normalized to the
molecular ion peak, wherein the molecular ion peak has 100%
relative abundance.
[0162] In other embodiments, a peak other than the molecular ion
peak can be the base peak. In such embodiments, all other fragment
peaks and/or molecular ion peak can be normalized with respect to
the base peak, wherein the base peak has 100% relative abundance,
to produce normalized fragment peaks and/or a normalized molecular
ion peak.
[0163] If a sample forms a molecular ion, it is likely to be the
heaviest ion (e.g., ion with the greatest mass-to-charge ratio
value) in the mass spectrum, and as such allows the identification
of the compound by its molecular weight. The molecular ion is
generally an ion formed by the removal from (positive ions) or
addition to (negative ions) a molecule of one electron without
fragmentation of the molecular structure. The mass of the molecular
ion corresponds to the sum of the masses of the most abundant
naturally occurring isotopes of the various atoms that make up the
molecule (with a correction for the masses of the electron(s) lost
or gained). As will be appreciated by one of skill in the art, and
with the help of this disclosure, some compounds do not have a
molecular ion present on the mass spectrum, because all of the
molecular ions break into fragments.
[0164] As will be appreciated by one of skill in the art, and with
the help of this disclosure, the way a compound (e.g., a molecule)
fragments depends upon the type of ionization used to ionize the
compound. Further, as will be appreciated by one of skill in the
art, and with the help of this disclosure, the fragmentation
pattern formed by an analyte will depend on the ionization
conditions and therefore is a controllable parameter within the
analysis.
[0165] In an embodiment, a fuel sample and/or a marked fuel mixture
can be subjected to GC-MS, wherein the MS ionization method
comprises electron ionization (EI), and wherein the ionization
energy of the MS can be equal to or greater than about 70 eV, which
effectively ionizes most organic compounds. In an embodiment, the
extent of ionization is controlled to preferentially afford
ionization of the analyte and heavy marker. This can be achieved by
a variety of methods, including varying the EI voltage, use of
chemical ionization with different chemical potentials, and
photoionization with different strengths and wavelengths of light
as non-limiting examples.
[0166] In an embodiment, the compound characterized by Formula I
when subjected to GC-MS using electron ionization can produce at
least one ion having a mass-to-charge ratio of equal to or greater
than about 300, alternatively from about 300 to about 600,
alternatively from about 400 to about 600, or alternatively from
about 500 to about 600, at an ionization energy of equal to or
greater than about 70 eV.
[0167] In an embodiment, the compound characterized by Formula I
when subjected to GC-MS using electron ionization can produce at
least one molecular ion having a mass-to-charge ratio of equal to
or greater than about 300, alternatively from about 300 to about
600, alternatively from about 400 to about 600, or alternatively
from about 500 to about 600, at an ionization energy of equal to or
greater than about 70 eV.
[0168] In an embodiment, the marked fuel composition can comprise
at least two compounds characterized by Formula I, wherein the
marked fuel composition can be subjected to GC-MS. Each of the fuel
markers of the marked fuel composition can display a unique mass
spectrum profile, and can provide for authenticating a fuel sample.
GC-MS can yield a mass spectrum displaying simultaneously
information about more than one fuel marker, provided that the fuel
markers have a different molecular weight, e.g., their molecular
ions have different mass-to-charge ratios.
[0169] In an embodiment, a method of determining adulteration of a
fuel can comprise subjecting to GC-MS a marked fuel mixture
comprising (a) fuel; (b) a compound characterized by Formula I; and
(c) a heavy compound, wherein the heavy compound comprises a
compound of Formula I having at least one atom replaced with an
isotope tag. As will be appreciated by one of skill in the art, and
with the help of this disclosure, MS can easily distinguish between
different isotopes of a given element, since MS separates and
detects ions of slightly different masses, such as for example
isotopes having a mass-to-charge ratio differing by +1 or more.
[0170] Generally, differences in mass among isotopes of an element
are very small, and the less abundant isotopes of an element are
typically very rare. As such, if an isotope tag as disclosed herein
is present in a compound, the signal of the isotope tag will be
greater than the natural abundance of such isotope, making it
possible to identify the heavy compound comprising the isotope tag.
As will be appreciated by one of skill in the art, and with the
help of this disclosure, the compound characterized by Formula I,
and the heavy compound, wherein the heavy compound comprises a
compound of Formula I having at least one atom replaced with an
isotope tag, elute simultaneously or nearly simultaneously in the
GC, and are analyzed simultaneously or nearly simultaneously on
MS.
[0171] In an embodiment, the compound characterized by Formula I
and the heavy compound comprising a compound of Formula I having at
least one atom replaced with an isotope tag can each display MS
peaks that are different (e.g., distinct, dissimilar, etc.) from
each other, thereby enabling simultaneous detection of both the
compound characterized by Formula I and the heavy compound.
[0172] Further, as will be appreciated by one of skill in the art,
and with the help of this disclosure, the abundance of each peak
corresponds to the amount of the compound that gave rise to that
particular peak.
[0173] In an embodiment, the base peak of a heavy compound
characterized by Formula I can comprise at least one isotope tag.
In some embodiments, the base peak of a heavy compound
characterized by Formula I can comprise all isotope tags of the
heavy compound characterized by Formula I. In an embodiment, the
molecular ion peak of a heavy compound characterized by Formula I
can comprise at least one isotope tag. In some embodiments, the
molecular ion peak of a heavy compound characterized by Formula I
can comprise all isotope tags of the heavy compound characterized
by Formula I.
[0174] In an embodiment, a method of determining adulteration of a
fuel can comprise (i) acquiring a fuel sample; (ii) subjecting the
fuel sample to .sup.13C NMR spectroscopy to yield .sup.13C NMR
data; and (iii) comparing the .sup.13C NMR data of the fuel sample
with the .sup.13C NMR data of the marked fuel composition (e.g.,
control data of the marked fuel composition). In such an
embodiment, the method can further comprise determining an amount
of the compound characterized by Formula I present in the
composition and the fuel sample based on the .sup.13C NMR data. NMR
spectroscopy is a research technique that exploits the magnetic
properties of certain atomic nuclei, such as for example hydrogen
(.sup.1H NMR) or carbon (.sup.13C NMR). Generally, NMR spectroscopy
relies on the phenomenon of nuclear magnetic resonance and can
provide detailed information about the structure, dynamics,
reaction state, and chemical environment of molecules. The
intramolecular magnetic field around an atom in a molecule changes
the resonance frequency, thus giving access to details of the
electronic structure of a molecule.
[0175] In an embodiment, a method of determining adulteration of a
fuel can comprise subjecting to .sup.13C NMR spectroscopy a marked
fuel mixture comprising (a) a fuel; (b) a compound characterized by
Formula I; and (c) a heavy compound, wherein the heavy compound
comprises a compound of Formula I having at least one atom replaced
with an isotope tag, wherein the isotope tag comprises carbon-13
(.sup.13C).
[0176] In an embodiment, a method of determining adulteration of a
fuel can comprise (i) acquiring a fuel sample; (ii) subjecting the
fuel sample to surface enhanced Raman scattering spectroscopy
(SERS) to yield SERS data; and (iii) comparing the SERS data of the
fuel sample with the SERS data of the marked fuel composition
(e.g., control data of the marked fuel composition). In such an
embodiment, the fuel sample can further be a marked fuel mixture.
Raman spectroscopy is a technique used to observe vibrational,
rotational, and other low-frequency modes in a molecule, which
renders it sensitive to isotopic substitution, due to low-frequency
modes in a molecule being influenced by the weight of the
individual atoms in the bonds that lead to those modes. Generally,
SERS is a surface-sensitive technique that enhances Raman
scattering by molecules adsorbed on rough metal surfaces or by
nanostructures such as plasmonic-magnetic silica nanotubes. SERS
can also be performed in colloidal solutions. SERS is an extremely
sensitive analytical technique and it has the potential of
detecting single molecules.
[0177] In an embodiment, a method of determining adulteration of a
fuel can comprise subjecting to SERS a marked fuel mixture
comprising (a) a fuel; (b) a compound characterized by Formula I;
and (c) a heavy compound, wherein the heavy compound comprises a
compound of Formula I having at least one atom replaced with an
isotope tag.
[0178] In some embodiments, determining adulteration of a fuel can
be complicated by matrix effects. Generally, a "matrix" refers to
an environment surrounding an analyte of interest (e.g., fuel
marker), such as for example fuel components, solvent, laundering
agents, masking agents, etc. In some cases, the matrix can
influence the result of detecting a particular analyte, by
interfering with the detection, an such interference can be
referred for purposes of the disclosure herein as "matrix
effect(s)." In some cases, matrix components can enhance transfer
of analytes (e.g., fuel markers) through GC (matrix induced
response enhancement); in other cases, matrix components can
decrease analyte responses (matrix induced diminishment). For
purposes of the disclosure herein, the term "matrix effects"
encompasses the many different root causes of error that can occur
in GC-based or GC-MS-based analyses as a result of matrix related
issues.
[0179] A conventional calibration process for a routine GC/MS
analysis can generally involve creating a series of accurately
prepared samples ("calibration standards") containing known but
varying concentrations of an analyte of interest (e.g., fuel
marker) in a suitable and readily available solvent. The
calibration standards can then be analyzed by GC-MS and a
calibration curve can be generated by plotting an analyte response
vs. a concentration of the analyte in the sample. Conventionally,
the concentration of analyte in unknown samples can be determined
by analyzing the unknown samples with the same methodology as the
calibration standards, followed by using the measured analyte
response to mathematically derive the concentration of the analyte
in the unknown sample from the relationship described by the
calibration curve. An increased accuracy of analyte detection
(e.g., accurate analyte quantitation) in GC-MS can be achieved when
a solvent used to create the calibration standards is closely
matched to the matrix of the unknown samples. For example,
isolating an analyte from a matrix can involve a step of extracting
the analyte from an aqueous solution into an organic solvent, such
as for example dichloromethane; it is likely that the most accurate
quantitation for the analyte could be achieved by using a "matrix
matched standard" method, wherein the calibration standards are
prepared in the same organic solvent (e.g., dichloromethane).
However, in some instances, even matching the matrix (e.g.,
matching a predominant solvent environment around an analyte) can
be insufficient to achieve a desired level of analytical
performance. In such instances, decreased analytical performance
can manifest as matrix effects (e.g., inaccurate quantitation,
decreased method ruggedness, low analyte detectability, reporting
of false positives or negative results, etc.).
[0180] In some embodiments, a method of determining adulteration of
a fuel can comprise subjecting a fuel sample to a method of
separating at least a portion of the fuel marker from at least a
portion of its fuel sample matrix by using any suitable
methodology, such as for example solid phase extraction (SPE).
Matrix effects can interfere in analysis of GC-MS-based markers in
fuels during fuel authentication, e.g., can prevent an accurate
quantitation of fuel markers by GC-MS. For example, matrix effects
can be problematic in fuel authentication analyses in areas or
countries where fuel composition varies greatly as a result of such
areas or countries using more than one fuel stream source, wherein
the fuel specifications and/or compositions are different for at
least two of the fuel stream sources, due to such areas or
countries only refining a portion of their fuel used internally;
such areas or countries purchasing a portion of their fuel from
outside suppliers; etc. Matrix effects can be greatly exacerbated
by the fact that many real world samples (which can be of unknown
pedigree) can be (and often are) adulterated with other substances
(e.g., adulterants, laundering agents, etc.), such as other fuels
types, industrial solvents, used oils, and the like, or
combinations thereof. Fuel adulteration is generally unknown prior
to a fuel authentication analysis, and since the existence of
adulterants can be unknown, appropriate instrument calibration and
generating a reliable calibration curve cannot be done under
conventional methodologies.
[0181] In an embodiment, a method of determining adulteration of a
fuel can further comprise subjecting a fuel sample (e.g., crude
oil, asphalt mixes, diesel fuel, etc.) to SPE. Generally, SPE is a
sample preparation technique that uses solid particles (e.g.,
chromatographic packing material) usually contained in a cartridge
type device (e.g., SPE column), to chemically separate the
different components of a sample, wherein samples are most often in
a liquid state. The different components of a sample would
generally elute in different fractions off the SPE column. SPE is
commonly used for removal of interferences from samples to
facilitate subsequent analysis of such samples.
[0182] In some embodiments, a fuel (e.g., fuel sample, marked fuel
mixture, etc.) can comprise a matrix, wherein the matrix can
comprise a non-interfering portion of the matrix (e.g.,
non-interfering components of the matrix) and an interfering
portion of the matrix (e.g., interfering components of the matrix).
The matrix generally refers to an environment surrounding the fuel
marker and/or the heavy compound, as previously disclosed herein.
In some embodiments, the interfering portion of the matrix can
comprise masking agents. Generally, a masking agent refers to any
agent (e.g., compound, substance, etc.) intentionally added to a
fuel with the purpose of interfering with authenticating the fuel,
e.g., with the purpose of interfering with accurately detecting the
presence and amount (e.g., concentration) of markers (e.g., fuel
markers) in the fuel. Nonlimiting examples of masking agents
include any substance not native to the fuel, such as crude oil,
used oil, solvents, other chemicals, and the like, or combinations
thereof.
[0183] In an embodiment, a method of determining adulteration of a
fuel can comprise (i) contacting a fuel sample with a heavy
compound to form a marked fuel mixture, wherein the fuel sample
comprises a fuel and a compound characterized by Formula I (e.g.,
fuel marker), and wherein the heavy compound comprises the compound
of Formula I having at least one atom replaced with an isotope tag;
(ii) subjecting the marked fuel mixture to SPE to yield a marked
fuel mixture fraction, wherein at least a portion of the fuel
marker and at least a portion of the heavy compound elute together
in the marked fuel mixture fraction; and (iii) subjecting to an
analytical technique the marked fuel mixture fraction to determine
fuel adulteration. In such an embodiment, the marked fuel mixture
can comprise a non-interfering portion of the matrix, interfering
components of the matrix, the compound characterized by Formula I,
and the heavy compound. SPE can separate at least a portion of
interfering components of the matrix from the compound
characterized by Formula I and the heavy compound, to yield a
marked fuel mixture fraction comprising the compound characterized
by Formula I and the heavy compound, wherein a concentration of the
interfering components of the matrix in the marked fuel mixture
fraction can be reduced by equal to or greater than about 75%,
alternatively greater than about 80%, alternatively greater than
about 85%, alternatively greater than about 90%, or alternatively
greater than about 95%, when compared to a concentration of the
interfering components of the matrix in the marked fuel mixture.
Interfering compounds that might be present in the marked fuel
mixture (e.g., masking agents, laundering agents, etc.) can be
removed by SPE, and as such the fraction containing the fuel marker
and the heavy compound can be further analyzed by any suitable
analytical technique (e.g., GC-MS). Even if SPE removes some of the
fuel marker and corresponding heavy compound from the marked fuel
mixture, the ratio of fuel marker to heavy compound is expected to
remain substantially the same, as both the marker and the
corresponding heavy compound would be removed from the fuel sample
to the same extent due to having the same chemical formula
differing only by the isotope tag(s). Further, the ratio of fuel
marker to corresponding heavy compound is expected to remain
substantially the same even if the dilution (e.g., concentration)
of the marker and the corresponding heavy compound changes in the
marked fuel mixture fraction as compared to the marked fuel
mixture. In some embodiments, the matrix comprises masking agents
(e.g., interfering components of the matrix).
[0184] In an embodiment, a fuel can be dually marked (e.g., fuel
sample can be marked with two different markers, wherein each
marker can be characterized by Formula I). In such an embodiment, a
dually marked fuel sample can be contacted with heavy compounds
corresponding to the two different markers that mark the fuel to
form a dually marked fuel mixture. The dually marked fuel mixture
can be further subjected to SPE to obtain marked fuel mixture
fractions, wherein each set of marker and corresponding heavy
compound can elute in separate (e.g., different, distinct)
fractions. Interfering compounds that might be present in the fuel
sample (e.g., masking agents) can be removed by SPE, and as such
the fractions containing each set of marker and corresponding heavy
compound can be further analyzed by any suitable analytical
technique (e.g., GC-MS). While the present disclosure discusses a
method of determining adulteration of a dually marked fuel, it
should be understood that such method or any steps thereof can be
applied in a method of determining adulteration of a fuel marked
with any suitable number of markers, such as for example three,
four, five, six, seven, eight, nine, ten, or more markers.
[0185] In an embodiment, a method of determining adulteration of a
fuel can further comprise contacting a fuel sample with a heavy
compound to form a marked fuel mixture; subjecting the marked fuel
mixture to SPE; recovering a marked fuel mixture fraction, wherein
the fraction comprises a fuel marker and corresponding heavy
compound, and wherein the fraction is substantially free of
interfering compounds (e.g., masking agents) that could have been
present in the fuel sample; and subjecting the marked fuel mixture
fraction to GC-MS analysis as previously described herein.
[0186] In an embodiment, a method of determining adulteration of a
fuel can further comprise contacting a dually marked fuel sample
with corresponding heavy compounds to form a dually marked fuel
mixture; subjecting the dually marked fuel mixture to SPE;
recovering marked fuel mixture fractions, wherein separate
fractions comprise each set of fuel marker and corresponding heavy
compound, and wherein such fractions are substantially free of
interfering compounds (e.g., masking agents) that could have been
present in the fuel sample; and subjecting the marked fuel mixture
fractions to GC-MS analysis as previously described herein.
[0187] In an embodiment, a fuel marker can comprise a compound
characterized by Formula I:
##STR00015##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.7
alkyl group, or a phenyl group; R.sup.3 and R.sup.3' can each
independently be hydrogen or a methyl group; R.sup.4 and R.sup.4'
can each independently be hydrogen, a methyl group, a tert-butyl
group, a cyclohexyl group, or a phenyl group; R.sup.5 and R.sup.5'
can each independently be a C.sub.6 or a C.sub.7 alkyl group;
R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.4 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a methyl group; and wherein the
compound characterized by Formula I when subjected to GC-MS using
electron ionization can produce at least one ion having a
mass-to-charge ratio of greater than about 300 at an ionization
energy of equal to or greater than about 70 eV.
[0188] In an embodiment, a method of forming a marked fuel
composition can comprise contacting (a) a fuel and (b) at least one
compound characterized by Formula I:
##STR00016##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.7
alkyl group, or a phenyl group; R.sup.3 and R.sup.3' can each
independently be hydrogen or a methyl group; R.sup.4 and R.sup.4'
can each independently be hydrogen, a methyl group, a tert-butyl
group, a cyclohexyl group, or a phenyl group; R.sup.5 and R.sup.5'
can each independently be a C.sub.6 or a C.sub.7 alkyl group;
R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.4 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a methyl group; and wherein the
compound characterized by Formula I when subjected to GC-MS using
electron ionization can produce at least one ion having a
mass-to-charge ratio of greater than about 300 at an ionization
energy of equal to or greater than about 70 eV.
[0189] In an embodiment, a method of determining adulteration of a
fuel can comprise subjecting to GC-MS a marked fuel composition
comprising (a) a fuel and (b) at least one compound characterized
by Formula I:
##STR00017##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.7
alkyl group, or a phenyl group; R.sup.3 and R.sup.3' can each
independently be hydrogen or a methyl group; R.sup.4 and R.sup.4'
can each independently be hydrogen, a methyl group, a tert-butyl
group, a cyclohexyl group, or a phenyl group; R.sup.5 and R.sup.5'
can each independently be a C.sub.6 or a C.sub.7 alkyl group;
R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.4 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a methyl group; and wherein the
compound characterized by Formula I when subjected to GC-MS using
electron ionization can produce at least one ion having a
mass-to-charge ratio of greater than about 300 at an ionization
energy of equal to or greater than about 70 eV.
[0190] In an embodiment, a method of determining adulteration of a
fuel can comprise subjecting to GC-MS a marked fuel mixture
comprising (a) a fuel; (b) a compound characterized by Formula
I:
##STR00018##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.7
alkyl group, or a phenyl group; R.sup.3 and R.sup.3' can each
independently be hydrogen or a methyl group; R.sup.4 and R.sup.4'
can each independently be hydrogen, a methyl group, a tert-butyl
group, a cyclohexyl group, or a phenyl group; R.sup.5 and R.sup.5'
can each independently be a C.sub.6 or a C.sub.7 alkyl group;
R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.4 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a methyl group; and (c) and a heavy
compound, wherein the heavy compound comprises a compound of
Formula I having at least one atom replaced with an isotope tag,
alternatively a plurality of the atoms are isotopically
substituted. In such an embodiment, the isotope tag comprises
deuterium (.sup.2H).
[0191] In an embodiment, a method of determining adulteration of a
fuel can comprise (i) contacting a fuel sample with a heavy
compound to form a marked fuel mixture, wherein the fuel sample
comprises a fuel and a compound characterized by Formula I:
##STR00019##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.20
alkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.3 and
R.sup.3' can each independently be hydrogen or a C.sub.1 to C.sub.4
alkyl group; R.sup.4 and R.sup.4' can each independently be
hydrogen, a C.sub.1 to C.sub.4 alkyl group, a C.sub.4 to C.sub.10
cycloalkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.5 and
R.sup.5' can each independently be a C.sub.4 to C.sub.10 alkyl
group; R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.6 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group; and
wherein the heavy compound comprises the compound of Formula I
having at least one atom replaced with deuterium; (ii) subjecting
the marked fuel mixture to solid phase extraction (SPE) to yield a
marked fuel mixture fraction, wherein at least a portion of the
compound characterized by Formula I and at least a portion of the
heavy compound elute together in the marked fuel mixture fraction;
and (iii) subjecting to gas chromatography-mass spectrometry
(GC-MS) the marked fuel mixture fraction to determine fuel
adulteration, wherein each of the compound characterized by Formula
I and the heavy compound when subjected to GC-MS using electron
ionization produces at least one ion having a mass-to-charge ratio
of from about 300 to about 600 at an ionization energy of equal to
or greater than about 70 eV. In such an embodiment, the compound
characterized by Formula I can have Structure F:
##STR00020##
and the heavy compound can have d-Structure F:
##STR00021##
[0192] In an embodiment, the marked fuel compositions as disclosed
herein advantageously display improvements in one or more
characteristics, when compared to similar compositions lacking a
fuel marker as disclosed herein. For example, the marked fuel
compositions can advantageously display enhanced detectability,
e.g., a lower amount of fuel marker can be used to mark fuel
compositions and enable determining the fuel adulteration.
[0193] In an embodiment, the fuel markers as disclosed herein
cannot be extracted (e.g., removed, taken out, etc.) from a marked
fuel composition by conventional means. For example, the fuel
marker cannot be substantially differentially adsorbed from a
marked fuel composition using conventional inexpensive adsorbents;
cannot be removed by extraction with acids, bases, or immiscible
solvents; cannot be easily oxidized, reduced or reacted with common
reagents to effectively remove the fuel marker; and the like.
Further, it should be difficult (e.g., not practical, not feasible
financially) to disguise the presence of the fuel marker by masking
the marker via reactions with masking agents.
[0194] In an embodiment, the fuel markers as disclosed herein
should not alter (e.g., modify, change, interfere with, etc.) the
properties of the fuel. In an embodiment, the fuel markers as
disclosed herein can be advantageously stable under conditions
(e.g., environmental conditions) that the fuel can be subjected
to.
[0195] In an embodiment, the fuel markers as disclosed herein can
advantageously display an adequate solubility in solvents for
marker delivery. For example, the fuel markers can be characterized
by a solubility in solvents of equal to or greater than about 50%,
alternatively from about 50% to about 20%, or alternatively from
about 20% to about 5% at 25.degree. C.
[0196] In an embodiment, the fuel markers as disclosed herein can
advantageously allow qualitative and/or quantitative authentication
of fuels, such as for example by GC-MS analysis. In an embodiment,
the fuel markers as disclosed herein can advantageously allow for
the use of small amounts (e.g., from about 1 ppb to about 50 ppm,
based on the total weight of the marked fuel composition) of fuel
markers as compared to other conventional markers.
[0197] In an embodiment, the fuel markers as disclosed herein can
allow for using and detecting more than one marker simultaneously,
such as for example by GC-MS. In such an embodiment, authentication
of a fuel can be accomplished by comparing more than one variable,
e.g., by simultaneously detecting the presence and/or concentration
of more than one fuel marker by GC-MS, for example.
[0198] In an embodiment, fuel markers and methods of using same as
disclosed herein can advantageously mitigate matrix effects.
Conventional analytical methods (e.g., matrix matched
standard-based calibrations with bracketing standards) for
analyzing fuel markers cannot accurately quantify markers in
refined petroleum products (e.g., fuels). In an embodiment, a
method of using the fuel markers to determine fuel adulteration as
disclosed herein can advantageously display improved detection
accuracy, without adding substantial sample preparation steps
(which can be both costly and time consuming), when compared to
conventional detection methods. Additional advantages of the marked
fuel compositions and methods of producing and using same as
disclosed herein can be apparent to one of skill in the art viewing
this disclosure.
EXAMPLES
[0199] The subject matter having been generally described, the
following examples are given as particular embodiments of the
disclosure and to demonstrate the practice and advantages thereof.
It is understood that the examples are given by way of illustration
and are not intended to limit the specification of the claims to
follow in any manner.
Example 1
[0200] The compound characterized by Structure F (i.e.,
bis(5-(tert-butyl)-2-methyl-4-(pentyloxy)phenyl)sulfane) was
synthesized by reaction of
4,4'-thiobis(2-(tert-butyl)-5-methylphenol)
(4,4'-thiobis(6-tert-butyl-m-cresol)) with 1-bromopentane,
according to the following reaction scheme:
##STR00022##
[0201] 4,4'-thiobis(2-(tert-butyl)-5-methylphenol)
(4,4'-thiobis(6-tert-butyl-m-cresol)) (1 equivalent (eq), 10 g,
27.89 mmol), potassium carbonate (2.5 eq, 9.6363 g, 69.725 mmol,
138.205 g/mol), and 1-bromopentane (2.1 eq, 8.8463 g, 7.3 mL,
58.569 mmol, 151.04 g/mol, d=1.218 g/mL) were dissolved in
N,N-dimethylformamide (DMF, 90 mL) at 90.degree. C. The reaction
was stirred until complete as determined by thin layer
chromatography (TLC). The reaction was poured into water and
extracted with ethyl acetate. The aqueous layer was discarded and
the ethyl acetate was back-extracted three times with brine to
remove residual DMF. The resulting organic solution was dried with
magnesium sulfate, filtered, and concentrated on a rotary
evaporator. The crude product was recrystallized from methanol,
filtered, and then washed with cold methanol. The product was dried
at 50.degree. C. under high vacuum for 12 hours to yield a fine
white powder (compound characterized by Structure F:
bis(5-(tert-butyl)-2-methyl-4-(pentyloxy)phenyl)sulfane). The yield
was 8.4211 g (60.5%).
Example 2
[0202] The compound characterized by Structure B (i.e.,
bis(4-(heptyloxy)phenyl)sulfane) was synthesized by reaction of
4,4'-thiodiphenol (bis(4-hydroxyphenyl) sulfide) with
1-bromoheptane, according to the following reaction scheme:
##STR00023##
[0203] 4,4'-thiodiphenol (bis(4-hydroxyphenyl) sulfide) (1 eq, 10
g, 45.8 mmol), potassium carbonate (2.5 eq, 15.8245 g, 114.5 mmol,
138.205 g/mol), and 1-bromoheptane (2.5 eq, 20.5070 g, 18 mL, 114.5
mmol, 179.10 g/mol, d=1.14 g/mL) were dissolved in DMF (100 mL) at
80.degree. C. The reaction was stirred until complete as determined
by TLC. The reaction was poured into water and extracted with
dichloromethane (DCM). The aqueous layer was discarded and the DCM
was back-extracted three times to remove residual DMF. The
resulting organic solution was dried with sodium sulfate, filtered,
and concentrated on a rotary evaporator. The product was
recrystallized from ethanol, filtered, and then washed with cold
ethanol. The product was subsequently put through a silica plug
with 50-50 hexanes-DCM and concentrated on a rotary evaporator to
yield a white powder (compound characterized by Structure B:
bis(4-(heptyloxy)phenyl)sulfane). The product was dried under high
vacuum for 24 hours at 50.degree. C. to remove residual solvents
and 1-bromoheptane. The yield was 5 g (26.3%)
Example 3
[0204] The compound characterized by Structure C (i.e.,
bis(4-(heptyloxy)-3-methylphenyl)sulfane) was synthesized by
reaction of 4,4'-thiobis(2-methylphenol)
(bis(4-hydroxy-3-methylphenyl) sulfide) with 1-bromoheptane,
according to the following reaction scheme:
##STR00024##
[0205] 4,4'-thiobis(2-methylphenol) (bis(4-hydroxy-3-methylphenyl)
sulfide) (1 eq, 10 g, 40.6 mmol), potassium carbonate (3.0 eq,
16.8334 g, 121.8 mmol, 138.205 g/mol), and 1-bromoheptane (3 eq, g,
21.8144 g, 19.2 mL, 121.8 mmol, 179.10 g/mol, d=1.14 g/mL) were
dissolved in DMF (150 mL) at 80.degree. C. The reaction was stirred
until complete as determined by TLC. The reaction was poured into
water and extracted with ethyl acetate. The aqueous layer was
discarded and the ethyl acetate was back-extracted three times to
remove residual DMF. The resulting organic solution was dried with
sodium sulfate, filtered, and concentrated on a rotary evaporator.
The product was recrystallized from ethanol, filtered, and then
washed with cold ethanol. The product (compound characterized by
Structure C: bis(4-(heptyloxy)-3-methylphenyl)sulfane) was dried at
50.degree. C. under high vacuum for 24 hours to remove residual
1-bromoheptane. The yield was 9.9320 g (55.3%).
Example 4
[0206] The compound characterized by Structure A (i.e.,
4,4'-oxybis((heptyloxy)benzene)) was synthesized by reaction of
4,4'-oxydiphenol (4,4'-dihydroxydiphenyl ether) with
1-bromopentane, according to the following reaction scheme:
##STR00025##
[0207] 4,4'-oxydiphenol (4,4'-dihydroxydiphenyl ether) (1 eq, 10 g,
49.5 mmol), potassium carbonate (2.5 eq, 17.1029 g, 123.75 mmol,
138.205 g/mol), and 1-bromoheptane (2.5 eq, 22.1636 g, 19.5 mL,
123.75 mmol, 179.10 g/mol, d=1.14 g/mL) were dissolved in DMF (100
mL) at 80.degree. C. The reaction was stirred until complete as
determined by TLC. The reaction was poured into water and filtered.
The crude product was taken up in methanol and heated while
stirring, followed by sonication. The suspension was then filtered
warm and the product washed with room temperature methanol to yield
a white powder (compound characterized by Structure A:
4,4'-oxybis((heptyloxy)benzene)). The yield was 16.3 g (83.6%).
Example 5
[0208] A deuterated compound characterized by Structure F,
d-Structure F (i.e.,
bis(5-(tert-butyl)-2-methyl-4-(pentyl-d.sub.22-oxy)phenyl)sulfane)
was synthesized by reaction of
4,4'-thiobis(2-(tert-butyl)-5-methylphenol)
(4,4'-thiobis(6-tert-butyl-m-cresol)) with deuterated
1-bromopentane (1-bromopentane-d.sub.11), according to the
following reaction scheme:
##STR00026##
[0209] 4,4'-thiobis(2-(tert-butyl)-5-methylphenol)
(4,4'-thiobis(6-tert-butyl-m-cresol)) (1 eq, 1.1641 g, 3.2467
mmol), potassium carbonate (2.1 eq, 0.9423 g, 6.8181 mmol, 138.205
g/mol), and 1-bromopentane-d.sub.11 (1.9 eq, 1 g, 6.1687 mmol,
162.11 g/mol) were dissolved in 10 mL DMF at 85.degree. C. The
reaction was stirred until complete as determined by TLC. The
reaction was poured into water and extracted with DCM. The aqueous
layer was discarded and the DCM was back-extracted three times to
remove residual DMF. The resulting organic solution was dried with
sodium sulfate, filtered, and concentrated on a rotary evaporator.
The product was subsequently put through a silica plug with 50-50
hexanes-DCM and concentrated on a rotary evaporator. The product
(deuterated compound characterized by Structure F, d-Structure F:
bis(5-(tert-butyl)-2-methyl-4-(pentyl-d.sub.22-oxy)phenyl)sulfane)
was dried under high vacuum for 24 hours at 50.degree. C. to remove
residual 1-bromopentane. The yield was 1 g (59.1%).
Example 6
[0210] A deuterated compound characterized by Structure B,
d-Structure B (i.e., bis(4-(heptyl-d.sub.30-oxy)phenyl)sulfane) was
synthesized by reaction of 4,4'-thiodiphenol (bis(4-hydroxyphenyl)
sulfide) with deuterated 1-bromoheptane (1-bromoheptane-d.sub.15),
according to the following reaction scheme:
##STR00027##
[0211] 4,4'-thiodiphenol (bis(4-hydroxyphenyl) sulfide) (1 eq,
1.1832 g, 5.4 mmol), potassium carbonate (2.1 eq, 1.57 g, 11.4
mmol, 138.205 g/mol), and 1-bromoheptane-d.sub.15 (1.9 eq, 2 g,
10.3 mmol, 194.19 g/mol) were dissolved in DMF (50 mL) at
85.degree. C. The reaction was stirred until complete as determined
by TLC. The reaction was poured into water and extracted with DCM.
The aqueous layer was discarded and the DCM was back-extracted
three times to remove residual DMF. The resulting organic solution
was dried with sodium sulfate, filtered, and concentrated on a
rotary evaporator. The product was recrystallized from ethanol,
filtered, and then washed with cold ethanol. The product was
subsequently put through a silica plug with 50-50 hexanes-DCM and
concentrated on a rotary evaporator to yield a white powder
(deuterated compound characterized by Structure B, d-Structure B:
bis(4-(heptyl-d.sub.30-oxy)phenyl)sulfane). The product was dried
under high vacuum for 24 hours at 50.degree. C. to remove residual
solvents and 1-bromoheptane. The yield was 1.2 g (50%).
Example 7
[0212] The identity of fuel samples was investigated. More
specifically, the concentration of fuel markers in various fuel
samples was investigated.
[0213] Sample and Standard Preparation.
[0214] Internal standard solutions were prepared by accurately
diluting the fuel sample and adding a heavy fuel marker as internal
standard to each diluted sample. For fuel marking, a concentrate of
fuel marker in toluene was prepared to a concentration of 50 ppm
(m/v) and added to the diesel fuel to yield a final concentration
of marker in diesel of 100 ppb (m/v).
[0215] Instrumentation.
[0216] GC-MS analyses were conducted on an Agilent 7890B Gas
Chromatograph equipped with an Agilent 5977A Mass Selective
Detector and an Agilent 7650 Automatic Liquid Sampler. A DB-35 ms
Ultra Inert column (15 m.times.0.250 mm.times.0.25 m) was connected
directly to a split/splitless inlet and to the mass spectrometer,
and a helium carrier was utilized. The method conditions for all
analyses were as follows: constant flow of 1.5 mL/min, inlet
temperature of 340.degree. C., pulsed splitless injection at 40 psi
for 0.5 min, temperature program at 150.degree. C. for 0.5 min,
then a 30.degree. C./min ramp to 300.degree. C. followed by a
20.degree. C./min ramp to 340.degree. C. (4 min hold), and a MS
transfer line temperature of 340.degree. C. MS quadrupole was
operated in selected ion monitoring (SIM) mode with two ions being
monitored for each analyte, and automated tuning was performed
using the ETUNE parameter set.
[0217] For analysis, internal standard and sample were co-injected
into the inlet via a 5 .mu.L syringe as a sandwich injection where
1 .mu.L of sample was co-injected with 0.5 .mu.L of the internal
standard solution. For samples in which the injection of no
internal standard was desired, a sandwich injection was still
performed so as to maintain the same analytical methodology for
comparison purposes, only the internal standard solution was
replaced by a sample of toluene.
[0218] GC-MS Analysis.
[0219] All samples were analyzed in triplicate and the three
results averaged for reporting purposes. A bracketing standard of
the marker in locally obtained diesel fuel was injected every fifth
injection and used to calculate the concentrations of the 5 diesel
fuel samples in the study.
[0220] Samples of diesel fuels (sample #1, sample #2, sample #3,
sample #4, and sample #5) from various fuel stations across the
globe were accurately marked with a compound characterized by
Structure F at a concentration of 100 ppb (m/v). These samples were
analyzed in triplicate and the resulting data are displayed in
Table 1 (ISTD=internal standard characterized by d-Structure F) and
FIG. 1.
TABLE-US-00001 TABLE 1 Calculated Fuel Fuel Marker Marker
Concentration Sample ID ISTD Response Response (ppb) Samples with
ISTD Diesel Standard 182,697 30,318 -- Sample #5 143,764 25,061
105.8 Sample #2 29,046 5,046 105.5 Sample #1 69,070 13,265 116.6
Sample #3 192,864 30,577 96.2 Sample #4 175,005 29,966 103.9 Diesel
Standard 180,052 29,843 -- Sample #5 138,817 24,761 108.3 Sample #2
28,689 4,818 101.9 Sample #1 70,016 12,845 111.4 Sample #3 190,001
30,702 98.1 Sample #4 179,007 29,391 99.7 Diesel Standard 179,656
29,852 -- Sample #5 142,773 24,382 103.7 Sample #2 28,408 5,029
107.5 Sample #1 69,699 13,002 113.2 Sample #3 191,564 30,497 96.6
Sample #4 179,568 29,387 99.3 Diesel Standard 178,788 29,810 --
Samples without ISTD Diesel Standard -- 30,663 -- Sample #5 --
25,709 83.4 Sample #2 -- 5,115 16.6 Sample #1 -- 13,292 43.1 Sample
#3 -- 31,964 103.7 Sample #4 -- 29,987 97.3 Diesel Standard --
30,994 -- Sample #5 -- 25,500 82.7 Sample #2 -- 5,090 16.5 Sample
#1 -- 13,353 43.3 Sample #3 -- 31,966 103.6 Sample #4 -- 30,169
97.8 Diesel Standard -- 30,711 -- Sample #5 -- 25,389 82.3 Sample
#2 -- 5,109 16.6 Sample #1 -- 13,272 43.0 Sample #3 -- 31,470 102.0
Sample #4 -- 30,442 98.6 Diesel Standard -- 31,015 --
[0221] For the standard analysis, a standard sample of diesel fuel
obtained locally (diesel standard) was marked with the compound
characterized by Structure F at a concentration of 100 ppb (m/v)
and run every fifth injection to serve as a bracketing standard.
The average response from the bracketing standards were determined
and used to calculate the concentration of marker in the different
fuel samples. FIG. 2 displays extracted ion chromatograms (498.3
m/z) for sample #1 and sample #3. In sample #3, the suppression of
the fuel marker is clearly evident as compared to sample #1, as
area counts for the marker around 6.7 minutes are very different
for the sample concentration of marker in both samples.
[0222] When the same samples were analyzed and a deuterated
internal standard was added (via co-injection for this example),
the calculated concentrations were far more accurate, as seen in
Table 1 and FIG. 1. The average predicted value using conventional
bracketing standard methodology was 69 ppb for the five diesel
samples (sample #1, sample #2, sample #3, sample #4, and sample
#5), whereas while using the internal standard methodology as
described here, the average concentration for the five diesel
samples was 104 ppb. The internal standard deuterated compound and
the fuel marker being suppressed by the matrix to the same extent
resulted in a dramatic improvement in accuracy. Therefore, by
taking a ratio of responses of the fuel marker to internal standard
(i.e., fuel marker response/internal standard response), instead of
just the fuel marker response, the signal suppression can be
mitigated and a much more accurate result can be determined.
[0223] Data Analysis.
[0224] The data was analyzed by using a conventional bracketing
standard approach, wherein a standard sample (labeled herein
"Diesel Standard") was a sample of diesel to which 100 ppb of
marker (characterized by Structure F) has been added. During the
analytical sequence, the "Diesel Standard" was injected prior to
(e.g., preceding) and following (e.g., succeeding) the samples of
unknown marker concentration. Generally, if a large number of
samples of unknown marker concentration have to be analyzed, then a
standard sample can be injected every 5-10 injections of samples of
unknown marker concentration. In all cases, the standard sample was
the same. In calculating the marker concentration of the samples
(#1, #2, #3, #4, #5, etc.), the response of the marker in the
standard injections surrounding (or bracketing: preceding,
succeeding, etc.) the samples was averaged and the response of each
sample was divided by the average response of the standard sample
(e.g., the bracketing standard) and multiplied by the concentration
of the marker in the standard sample according to equation (1):
C x = 2 .times. R x ( R Std 1 + R Std 2 ) .times. C Std ( 1 )
##EQU00001##
wherein C.sub.x=concentration of the marker in sample X of unknown
marker concentration; wherein R.sub.x=marker response in the sample
X of unknown marker concentration; wherein R.sub.Std 1=marker
response of the standard sample preceding the sample X of unknown
marker concentration; wherein R.sub.Std 2=marker response of the
standard sample succeeding the sample X of unknown marker
concentration; wherein C.sub.Std=concentration of the marker in the
standard sample; and wherein R.sub.Std 1 and R.sub.Std 2 are
different injections of the same standard sample having a marker
concentration of C.sub.Std. For purposes of the disclosure herein,
"response" refers to the magnitude of the analytical signal or
response. Similarly, the concentration of the marker in fuel
samples can be calculated by utilizing the ISTD as described
herein, according to equation (2):
C x = 2 .times. RR X ( RR Std 1 + RR Std 2 ) .times. C Std ( 2 )
##EQU00002##
wherein C.sub.x=concentration of the marker in sample X of unknown
marker concentration; wherein RR.sub.X=marker response ratio, or
marker response/ISTD response for sample X of unknown marker
concentration; wherein RR.sub.Std 1=marker response ratio, or
marker response/ISTD response of the standard sample preceding the
sample X of unknown marker concentration; wherein RR.sub.Std
2=marker response ratio, or marker response/ISTD response of the
standard sample succeeding the sample X of unknown marker
concentration; wherein C.sub.Std=concentration of the marker in the
standard sample; and wherein R.sub.Std 1 and R.sub.Std 2 are
different injections of the same standard sample having a marker
concentration of C.sub.Std. As will be appreciated by one of skill
in the art, and with the help of this disclosure, while the
concentrations were calculated herein by using a single point
calibration for simplicity, the principles of marker to internal
standard response ratios can be applied to any multipoint
calibration curve or calibration process to enhance the accuracy of
the calculated marker concentration.
[0225] It is noteworthy from the data collected (Table 1, FIGS. 1
and 2) that even using a matrix matched standard gave very poor
accuracy when analyzing diesel samples of different origin. These
data speak to the fact that diesel fuel, and virtually all
hydrocarbon-based fuels can be highly variable in nature. The
source of the crude oil, refining conditions, age, and
environmental storage conditions all have a dramatic impact on the
chemical composition of the fuel. Further, these differences can
have a significant impact on the analysis of chemical fuel markers
added to fuels to aide in their identification/authentication.
Example 8
[0226] The identity of fuel samples was investigated. More
specifically, the concentration of fuel markers in various fuel
samples was investigated prior to and subsequent to solid phase
extraction (SPE). Fuel samples and analysis were prepared and
conducted as described in Example 7.
[0227] Samples were acquired and marked with a compound
characterized by Structure F as described in Example 7. Sample #1,
sample #2, and sample #5 of Example 7 were analyzed prior to and
subsequent to SPE. Upon SPE, the samples were labeled sample #1a,
sample #2a, and sample #5a, respectively. For SPE analysis, a
solution of ISTD (characterized by d-Structure F) in hexane (3 mL)
(e.g., ISTD hexane solution) was added to 0.225 mL of the fuel
sample of unknown marker concentration to form an unknown sample in
ISTD hexane solution, which was mixed to ensure complete
dissolution. A 1 g silica gel SPE cartridge was conditioned with 5
mL of hexane prior to the addition of 2 mL of the unknown sample in
ISTD hexane solution. After the entire unknown sample in ISTD
hexane solution passed through the SPE column, the SPE column was
rinsed with 16 mL of hexane to remove interferences from the sample
of unknown marker concentration. The ISTD and marker were then
eluted from the SPE column with 2 mL of toluene into a vial which
was then analyzed directly via GC-MS.
[0228] All samples were analyzed in triplicate and the resulting
data are displayed in Table 2 (ISTD=internal standard characterized
by d-Structure F).
TABLE-US-00002 TABLE 2 Fuel Marker Calculated Fuel Marker Sample ID
ISTD Response Response Concentration (ppb) Samples Post-SPE Cleanup
Diesel Standard 75,700 2,227 -- Sample #5a 118,209 3841 96.5 Sample
#2a 128,047 4491 104.1 Sample #1a 130,170 4530 103.3 Diesel
Standard 84,104 2,474 -- Sample #5a 120,835 3,976 97.7 Sample #2a
129,746 4,606 105.4 Sample #1a 128,500 4,506 104.1 Diesel Standard
88,641 2,667 -- Sample #5a 134,858 4,472 98.4 Sample #2a 128,014
4,522 104.9 Sample #1a 139,587 4,968 105.6 Diesel Standard 92,185
2,795 -- Samples Pre-SPE Cleanup Diesel Standard -- 30,663 --
Sample #5 -- 25,709 83.4 Sample #2 -- 5,115 16.6 Sample #1 --
13,292 43.1 Diesel Standard -- 30,994 -- Sample #5 -- 25,500 82.7
Sample #2 -- 5,090 16.5 Sample #1 -- 13,353 43.3 Diesel Standard --
30,711 -- Sample #5 -- 25,389 82.3 Sample #2 -- 5,109 16.6 Sample
#1 -- 13,272 43.0 Diesel Standard -- 31,015 --
[0229] FIG. 3A displays extracted ion chromatograms (498.4 m/z) for
sample #1, sample #2 and sample #5, prior to SPE. FIG. 3B displays
extracted ion chromatograms (498.4 m/z) for sample #1a, sample #2a
and sample #5a, subsequent to SPE. As seen from FIG. 3B as compared
to FIG. 3A, when the analyzed samples were subjected to SPE, the
calculated concentrations were far more accurate. This dramatic
increase in accuracy stems from the fact that the interferences
present in the diesel samples, which dramatically impact the
accurate quantitation of the marker, are removed by the SPE process
and hence the responses obtained from the analysis are more
consistent across the fuel samples, similarly to the inclusion of
the ISTD in the analysis, which provides additional enhanced
accuracy to the analysis.
[0230] For the purpose of any U.S. national stage filing from this
application, all publications and patents mentioned in this
disclosure are incorporated herein by reference in their
entireties, for the purpose of describing and disclosing the
constructs and methodologies described in those publications, which
might be used in connection with the methods of this disclosure.
Any publications and patents discussed herein are provided solely
for their disclosure prior to the filing date of the present
application. Nothing herein is to be construed as an admission that
the inventors are not entitled to antedate such disclosure by
virtue of prior invention.
[0231] In any application before the United States Patent and
Trademark Office, the Abstract of this application is provided for
the purpose of satisfying the requirements of 37 C.F.R. .sctn.1.72
and the purpose stated in 37 C.F.R. .sctn.1.72(b) "to enable the
United States Patent and Trademark Office and the public generally
to determine quickly from a cursory inspection the nature and gist
of the technical disclosure." Therefore, the Abstract of this
application is not intended to be used to construe the scope of the
claims or to limit the scope of the subject matter that is
disclosed herein. Moreover, any headings that can be employed
herein are also not intended to be used to construe the scope of
the claims or to limit the scope of the subject matter that is
disclosed herein. Any use of the past tense to describe an example
otherwise indicated as constructive or prophetic is not intended to
reflect that the constructive or prophetic example has actually
been carried out.
[0232] The present disclosure is further illustrated by the
following examples, which are not to be construed in any way as
imposing limitations upon the scope thereof. On the contrary, it is
to be clearly understood that resort can be had to various other
aspects, embodiments, modifications, and equivalents thereof which,
after reading the description herein, can be suggest to one of
ordinary skill in the art without departing from the spirit of the
present invention or the scope of the appended claims.
ADDITIONAL DISCLOSURE
[0233] A first embodiment, which is a composition comprising: (a) a
fuel and (b) at least one compound characterized by Formula I:
##STR00028##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.20
alkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.3 and
R.sup.3' can each independently be hydrogen or a C.sub.1 to C.sub.4
alkyl group; R.sup.4 and R.sup.4' can each independently be
hydrogen, a C.sub.1 to C.sub.4 alkyl group, a C.sub.4 to C.sub.10
cycloalkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.5 and
R.sup.5' can each independently be a C.sub.4 to C.sub.10 alkyl
group; R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.6 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group; and
wherein the compound characterized by Formula I when subjected to
gas chromatography-mass spectrometry (GC-MS) using electron
ionization produces at least one ion having a mass-to-charge ratio
of from about 300 to about 600 at an ionization energy of equal to
or greater than about 70 eV.
[0234] A second embodiment, which is the composition of the first
embodiment, wherein X is O or S and R.sup.1 and R.sup.2 are lone
non-bonding electron pairs.
[0235] A third embodiment, which is the composition of any one of
the first and the second embodiments, wherein the compound
characterized by Formula I has Structure A:
##STR00029##
[0236] A fourth embodiment, which is the composition of any one of
the first and the second embodiments, wherein the compound
characterized by Formula I has Structures B-F:
##STR00030##
[0237] A fifth embodiment, which is the composition of the first
embodiment, wherein X is C and R.sup.1 and R.sup.2 each
independently are selected from the group consisting of a methyl
group, an ethyl group, a n-propyl group, an iso-propyl group, a
n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl
group, a pentyl group, a n-pentyl group, an iso-pentyl group, a
sec-pentyl group, a hexyl group, a heptyl group, an octyl group, a
nonyl group, a decyl group, a undecyl group, a dodecyl group, a
tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl
group, a heptadecyl group, an octadecyl group and a nonadecyl
group.
[0238] A sixth embodiment, which is the composition of the first
embodiment, wherein the compound characterized by Formula I has any
of Structures G-O:
##STR00031## ##STR00032##
[0239] A seventh embodiment, which is the composition of the first
embodiment, wherein X is C and R.sup.1 and R.sup.2 can each
independently be hydrogen, a C.sub.1 to C.sub.10 alkyl group, or a
C.sub.6 to C.sub.10 aryl group.
[0240] An eighth embodiment, which is the composition of the
seventh embodiment, wherein the C.sub.6 to C.sub.10 aryl group is
phenyl, a substituted phenyl, tolyl, a substituted tolyl, xylyl or
a substituted xylyl.
[0241] A ninth embodiment, which is the composition of any one of
the seventh and the eighth embodiments, wherein the compound
characterized by Formula I has Structure P:
##STR00033##
[0242] A tenth embodiment, which is the composition of the first
embodiment, wherein X is C and R.sup.3 and R.sup.3' can each
independently be a methyl group or hydrogen.
[0243] An eleventh embodiment, which is the composition of the
first embodiment, wherein X is C and R.sup.4, R.sup.4', R.sup.5,
and R.sup.5 can each independently be a C.sub.1 to C.sub.10 alkyl
group, a C.sub.4 to C.sub.10 cycloalkyl group, or a C.sub.6 to
C.sub.10 aryl group.
[0244] A twelfth embodiment, which is the composition of the
eleventh embodiment, wherein the C.sub.4 to C.sub.10 cycloalkyl
group is a cyclobutyl group, a substituted cyclobutyl group, a
cyclopentyl group, a substituted cyclopentyl group, a cyclohexyl
group, a substituted cyclohexyl group, a cycloheptyl group, a
substituted cycloheptyl group, a cyclooctyl group, or a substituted
cyclooctyl group.
[0245] A thirteenth embodiment, which is the composition of the
first embodiment, wherein R.sup.4 and R.sup.4' are hydrogen.
[0246] A fourteenth embodiment, which is the composition of the
first embodiment, wherein R.sup.4 and R.sup.4' can each
independently be hydrogen or a tert-butyl group.
[0247] A fifteenth embodiment, which is the composition of the
first embodiment, wherein X is C, R.sup.1 and R.sup.2 are a methyl
group, and R.sup.5 and R.sup.5' are both a C.sub.4 to C.sub.10
alkyl group.
[0248] A sixteenth embodiment, which is the composition of the
fifteenth embodiment, wherein R.sup.5 and R.sup.5' are both a
pentyl group or a heptyl group.
[0249] A seventeenth embodiment, which is the composition of the
first embodiment, wherein R.sup.6 and R.sup.6' each independently
are selected from the group consisting of a methyl group, an ethyl
group, a n-propyl group, an iso-propyl group, a n-butyl group, an
iso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl
group, a n-pentyl group, an iso-pentyl group, a sec-pentyl group
and a hexyl group.
[0250] An eighteenth embodiment, which is the composition of any
one of the first through the seventeenth embodiments, wherein the
fuel comprises gasoline, diesel, jet fuel, kerosene, non-petroleum
derived fuels, alcohol fuels, ethanol, methanol, propanol, butanol,
biodiesel, maritime fuels, or combinations thereof.
[0251] A nineteenth embodiment, which is the composition of any one
of the first through the eighteenth embodiments, wherein the
compound characterized by Formula I is present in an amount of from
about 1 ppb to about 50 ppm, based on the total weight of the
composition.
[0252] A twentieth embodiment, which is a compound characterized by
Formula I:
##STR00034##
wherein X can be carbon (C), oxygen (O), or sulfur (S); R.sup.1 and
R.sup.2 can each independently be hydrogen, a C.sub.1 to C.sub.20
alkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.3 and
R.sup.3' can each independently be hydrogen or a C.sub.1 to C.sub.4
alkyl group; R.sup.4 and R.sup.4' can each independently be
hydrogen, a C.sub.1 to C.sub.4 alkyl group, a C.sub.4 to C.sub.10
cycloalkyl group, or a C.sub.6 to C.sub.10 aryl group; R.sup.5 and
R.sup.5' can each independently be a C.sub.4 to C.sub.10 alkyl
group; R.sup.6 and R.sup.6' can each independently be hydrogen or a
C.sub.1 to C.sub.6 alkyl group; and R.sup.7 and R.sup.7' can each
independently be hydrogen or a C.sub.1 to C.sub.4 alkyl group; and
wherein the compound characterized by Formula I when subjected to
gas chromatography-mass spectrometry (GC-MS) using electron
ionization produces at least one ion having a mass-to-charge ratio
of greater than about 300 at an ionization energy of equal to or
greater than about 70 eV.
[0253] A twenty-first embodiment, which is the compound of the
twentieth embodiment, wherein X is O or S and R.sup.1 and R.sup.2
are lone non-bonding electron pairs.
[0254] A twenty-second embodiment, which is the compound of any one
of the twentieth and the twenty-first embodiments, wherein the
compound characterized by Formula I has Structure A:
##STR00035##
[0255] A twenty-third embodiment, which is the compound of any one
of the twentieth and the twenty-first embodiments, wherein the
compound characterized by Formula I has Structures B-F:
##STR00036##
[0256] A twenty-fourth embodiment, which is the compound of the
twentieth embodiment, wherein X is C and R.sup.1 and R.sup.2 each
independently are selected from the group consisting of a methyl
group, an ethyl group, a n-propyl group, an iso-propyl group, a
n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl
group, a pentyl group, a n-pentyl group, an iso-pentyl group, a
sec-pentyl group, a hexyl group, a heptyl group, an octyl group, a
nonyl group, a decyl group, a undecyl group, a dodecyl group, a
tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl
group, a heptadecyl group, an octadecyl group and a nonadecyl
group.
[0257] A twenty-fifth embodiment, which is the compound of the
twentieth embodiment, wherein the compound characterized by Formula
I has any of Structures G-O:
##STR00037## ##STR00038##
[0258] A twenty-sixth embodiment, which is the compound of the
twentieth embodiment, wherein X is C and R.sup.1 and R.sup.2 can
each independently be hydrogen, a C.sub.1 to C.sub.10 alkyl group,
or a C.sub.6 to C.sub.10 aryl group.
[0259] A twenty-seventh embodiment, which is the compound of the
twenty-sixth embodiment, wherein the C.sub.6 to C.sub.10 aryl group
is phenyl, a substituted phenyl, tolyl, a substituted tolyl, xylyl
or a substituted xylyl.
[0260] A twenty-eighth embodiment, which is the compound of any one
of the twenty-sixth and the twenty-seventh embodiments, wherein the
compound characterized by Formula I has Structure P:
##STR00039##
[0261] A twenty-ninth embodiment, which is the compound of the
twentieth embodiment, wherein X is C and R.sup.3 and R.sup.3' can
each independently be a methyl group or hydrogen.
[0262] A thirtieth embodiment, which is the compound of the
twentieth embodiment, wherein X is C and R.sup.4, R.sup.4',
R.sup.5, and R.sup.5' can each independently be a C.sub.1 to
C.sub.10 alkyl group, a C.sub.4 to C.sub.10 cycloalkyl group, or a
C.sub.6 to C.sub.10 aryl group.
[0263] A thirty-first embodiment, which is the compound of the
thirtieth embodiment, wherein the C.sub.4 to C.sub.10 cycloalkyl
group is a cyclobutyl group, a substituted cyclobutyl group, a
cyclopentyl group, a substituted cyclopentyl group, a cyclohexyl
group, a substituted cyclohexyl group, a cycloheptyl group, a
substituted cycloheptyl group, a cyclooctyl group, or a substituted
cyclooctyl group.
[0264] A thirty-second embodiment, which is the compound of the
twentieth embodiment, wherein R.sup.4 and R.sup.4' are
hydrogen.
[0265] A thirty-third embodiment, which is the compound of the
twentieth embodiment, wherein R.sup.4 and R.sup.4' can each
independently be hydrogen or a tert-butyl group.
[0266] A thirty-fourth embodiment, which is the compound of the
twentieth embodiment, wherein X is C, R.sup.1 and R.sup.2 are a
methyl group, and R.sup.5 and R.sup.5' are both a C.sub.4 to
C.sub.10 alkyl group.
[0267] A thirty-fifth embodiment, which is the compound of the
thirty-fourth embodiment, wherein R.sup.5 and R.sup.5' are both a
pentyl group or a heptyl group.
[0268] A thirty-sixth embodiment, which is the compound of the
twentieth embodiment, wherein R.sup.6 and R.sup.6' each
independently are selected from the group consisting of a methyl
group, an ethyl group, a n-propyl group, an iso-propyl group, a
n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl
group, a pentyl group, a n-pentyl group, an iso-pentyl group, a
sec-pentyl group and a hexyl group.
[0269] While embodiments of the disclosure have been shown and
described, modifications thereof can be made without departing from
the spirit and teachings of the invention. The embodiments and
examples described herein are exemplary only, and are not intended
to be limiting. Many variations and modifications of the invention
disclosed herein are possible and are within the scope of the
invention.
[0270] Accordingly, the scope of protection is not limited by the
description set out above but is only limited by the claims which
follow, that scope including all equivalents of the subject matter
of the claims. Each and every claim is incorporated into the
specification as an embodiment of the present invention. Thus, the
claims are a further description and are an addition to the
detailed description of the present invention. The disclosures of
all patents, patent applications, and publications cited herein are
hereby incorporated by reference.
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