U.S. patent application number 10/565127 was filed with the patent office on 2007-01-04 for coated closure for performing direct vial surface sorbent microextraction.
Invention is credited to Robert H. Wohleb.
Application Number | 20070003441 10/565127 |
Document ID | / |
Family ID | 34274488 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070003441 |
Kind Code |
A1 |
Wohleb; Robert H. |
January 4, 2007 |
Coated closure for performing direct vial surface sorbent
microextraction
Abstract
A device for extracting an analyte from a sample matrix
comprises a sorption cap or closure which is coated on the inside
surface with a sorbent material. A method for extracting an analyte
from a sample matrix includes exposing the cap sorptive coating to
the sample matrix by sealing the sample bottle or vial with the
sorption cap. After the analyte is collected in the sorbent
material, the sorption cap may be removed from the sample container
and used to seal an analytical vial containing a small amount of an
elution solvent. The analytical vial with sorptive cap may then be
stored or transported to a lab for further analysis.
Inventors: |
Wohleb; Robert H.; (GIG
HARBOR, WA) |
Correspondence
Address: |
Keeling Hudson
901 North Post Oak Road
Houston
TX
77024-3845
US
|
Family ID: |
34274488 |
Appl. No.: |
10/565127 |
Filed: |
September 16, 2004 |
PCT Filed: |
September 16, 2004 |
PCT NO: |
PCT/US04/30262 |
371 Date: |
January 18, 2006 |
Current U.S.
Class: |
422/400 |
Current CPC
Class: |
G01N 1/405 20130101;
B01L 2300/042 20130101; Y10T 436/25375 20150115; B01L 2200/0631
20130101; B01L 2300/047 20130101; G01N 2001/4061 20130101; B01L
2300/046 20130101; B01L 2300/069 20130101; B01L 3/50825 20130101;
Y10T 436/255 20150115; G01N 1/34 20130101 |
Class at
Publication: |
422/099 |
International
Class: |
B01L 3/00 20060101
B01L003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 16, 2003 |
US |
10/663955 |
Claims
1. A device for the collection and extraction of at least one
analyte within a sample, said device comprising: a vessel; said
vessel defining a chamber for holding said sample; said chamber
having an opening therein; a neck around said opening extending
away from said chamber; a cap; said cap selectively attachable to
said neck; said cap having a top cover interior surface in
communication with said chamber; said top cover interior surface
having a coated surface; said coated surface facing said chamber;
and said coated surface having a sorptive coating.
2. The device of claim 1, wherein said sorptive coating comprises
at least one selection from the group consisting of: (a) an
immobilized polysiloxane polymer, having two attached functional
groups, wherein the first attached functional group is selected
from the group consisting of: alkyl, alkenyl, alkynyl, aryl,
alkylaryl, alkenylaryl, alkynylaryl, haloalkyl, and haloaryl, and
the second attached functional group is selected from the group
consisting of: alkyl, alkenyl, alkynyl, aryl, alkylaryl,
alkenylaryl, alkynylaryl, haloalkyl, and haloaryl; (b) a porous
layer; (c) other immobilized polymers above their glass transition
temperature; (d) an immobilized porous polymer; (e) a sol gel; (f)
an immobilized adsorbent; and (g) derivatized silica.
3. The device of claim 1, further comprising: said cap comprising a
top cover and a sidewall; said coated surface being on the interior
surface of said top cover; said top cover having a periphery; said
sidewall attached to said top cover around said periphery to define
a cavity bounded by said sidewall and said top cover; said coated
surface being inside said cavity; said neck receivable within said
cavity; and said sidewall engaging said neck.
4. The device of claim 1, further comprising: said top cover
including a syringe-permeable orifice.
5. (canceled)
6. (canceled)
7. (canceled)
8. A device for the collection and extraction of at least one
analyte within a sample, said device comprising: a vessel; said
vessel defining a chamber for holding said sample; said chamber
having an opening therein; a neck around said opening extending
away from said chamber; a cap; said cap selectively attachable to
said neck; said cap having a top cover interior surface in
communication with said chamber; said top cover interior surface
having a coated surface; said coated surface facing said chamber;
and said coated surface having a particulate coating.
9. The device of claim 8, wherein said particulate coating
comprises at least one selection from the group consisting of: (a)
molecular sieves; (b) activated alumina; (c) silica; (d) silica
gel; (e) ion exchange resins; and (f) desiccant.
10. (canceled)
11. (canceled)
12. (canceled)
13. (canceled)
14. (canceled)
15. A device for the collection and extraction of at least one
analyte within a sample, said device comprising: a vessel; said
vessel defining a chamber for holding said sample; said chamber
having an opening therein; a neck around said opening extending
away from said chamber; a cap; said cap selectively attachable to
said neck; said cap having a top cover interior surface in
communication with said chamber; said top cover interior surface
having a coated surface; said coated surface facing said chamber;
said coated surface selected from the group consisting of: sorptive
coating and particulate coating; said sorptive coating comprises at
least one selection from the group consisting of: (a) an
immobilized polysiloxane polymer, having two attached functional
groups, wherein the first attached functional group is selected
from the group consisting of: alkyl, alkenyl, alkynyl, aryl,
alkylaryl, alkenylaryl, alkynylaryl, haloalkyl, and haloaryl, and
the second attached functional group is selected from the group
consisting of: alkyl, alkenyl, alkynyl, aryl, alkylaryl,
alkenylaryl, alkynylaryl, haloalkyl, and haloaryl; (b) a porous
layer; (c) other immobilized polymers above their glass transition
temperature; (d) an immobilized porous polymer; (e) a sol gel; (f)
an immobilized adsorbent; and (g) derivatized silica; said
particulate coating comprises at least one selection from the group
consisting of: (a) molecular sieves; (b) activated alumina; (c)
silica; (d) silica gel; (e) ion exchange resins, and (f) desiccant;
and said cover including a syringe-permeable orifice.
16. A cap for collecting a selected analyte from an analyte-bearing
sample when said cap is in communication with a vessel, wherein
said cap comprises: a cover member having an outer cover periphery;
a sidewall extending from said cover member about said outer cover
periphery to define a cavity; said cavity bounded by said sidewall
and said cover member; said cover member having a coated surface
inside said cavity; said cavity receiving said vessel; said
sidewall engaging the neck of said vessel; and said coated surface
having a sorptive coating.
17. The cap of claim 16, wherein said sorptive coating comprises at
least one selection from the group consisting of: (a) an
immobilized polysiloxane polymer, having two attached functional
groups, wherein the first attached functional group is selected
from the group consisting of: alkyl, alkenyl, alkynyl, aryl,
alkylaryl, alkenylaryl, alkynylaryl, haloalkyl, and haloaryl, and
the second attached functional group is selected from the group
consisting of: alkyl, alkenyl, alkynyl, aryl, alkylaryl,
alkenylaryl, alkynylaryl, haloalkyl, and haloaryl; (b) a porous
layer; (c) other immobilized polymers above their glass transition
temperature; (d) an immobilized porous polymer; (e) a sol gel; (f)
an immobilized adsorbent; and (g) derivatized silica.
18. The cap of claim 17, further comprising: said cover member
including a syringe-permeable orifice.
19. (canceled)
20. (canceled)
21. A cap for collecting a selected contaminant from a sample when
said cap is in communication with a vessel, wherein said cap
comprises: a cover member having an outer cover periphery; a
sidewall extending from said cover member about said outer cover
periphery to define a cavity; said cavity bounded by said sidewall
and said cover member; said cover member having a coated surface
inside said cavity; said cavity receiving said vessel; said
sidewall engaging the neck of said vessel; and said coated surface
having a particulate coating.
22. The cap of claim 21, wherein said particulate coating comprises
at least one selection from the group consisting of: (a) molecular
sieves; (b) activated alumina; (c) silica; (d) silica gel; (e) ion
exchange resins, and; (f) desiccant;
23. (canceled)
24. (canceled)
25. (canceled)
26. A cap for closing a vessel, said vessel including a vessel
wall, a chamber, and a neck, said neck extending outward from said
vessel wall, said neck defining an opening therein providing fluid
communication to said chamber, said neck including an outer neck
surface, a rim and an inner rim periphery, said cap comprising: a
lower periphery, a cover periphery, a sidewall, and a coated
surface; said sidewall being between said lower periphery and said
cover periphery; said coated surface located within said lower
periphery; said lower periphery being smaller than said cover
periphery; said inner neck periphery being larger than said lower
periphery and smaller than said cover periphery; and said neck
receiving said cap such that said sidewall fits within said inner
neck periphery in an interference fit.
27. The cap of claim 26, wherein said coated surface is a sorptive
coating comprising at least one selection from the group consisting
of: (a) an immobilized polysiloxane polymer, having two attached
functional groups, wherein the first attached functional group is
selected from the group consisting of: alkyl, alkenyl, alkynyl,
aryl, alkylaryl, alkenylaryl, alkynylaryl, haloalkyl, and haloaryl,
and the second attached functional group is selected from the group
consisting of: alkyl, alkenyl, alkynyl, aryl, alkylaryl,
alkenylaryl, alkynylaryl, haloalkyl, and haloaryl; (b) a porous
layer; (c) other immobilized polymers above their glass transition
temperature; (d) an immobilized porous polymer; (e) a sol gel; (f)
an immobilized adsorbent; and (g) derivatized silica.
28. The cap of claim 26, wherein said coated surface is a
particulate coating comprising at least one selection from the
group consisting of: (a) molecular sieves; (b) activated alumina;
(c) silica; (d) silica gel; (e) ion exchange resins, and; (f)
desiccant;
29. A method for extraction and desorption of one or more analytes
in an analyte-bearing sample, said method comprising: coating an
inner surface of a first cap with a sorptive coating; attaching
said first cap to a first vessel containing said analyte-bearing
sample; exposing said sorptive coating to said analyte-bearing
sample; agitating said first vessel to expose said coating to said
analyte-bearing sample for a predetermined period of time;
sorptively extracting at least one analyte from said
analyte-bearing sample; removing said first cap from said first
vessel; attaching a second cap to said first vessel; attaching said
first cap to a second vessel; said second vessel containing a
solvent; agitating said second vessel to expose said
analyte-bearing coating to said solvent; desorbing at least one
analyte from said analyte-bearing coating into said solvent; and
injecting said analyte-bearing solvent into an analytical
device.
30. The method of claim 29, wherein said sorptive coating comprises
at least one selection of the group consisting of: (a) an
immobilized polysiloxane polymer, having two attached functional
groups, wherein the first attached functional group is selected
from the group consisting of: alkyl, alkenyl, alkynyl, aryl,
alkylaryl, alkenylaryl, alkynylaryl, haloalkyl, and haloaryl, and
the second attached functional group is selected from the group
consisting of: alkyl, alkenyl, alkynyl, aryl, alkylaryl,
alkenylaryl, alkynylaryl, haloalkyl, and haloaryl; (b) a porous
layer; (c) other immobilized polymers above their glass transition
temperature; (d) an immobilized porous polymer; (e) a sol gel; (f)
an immobilized adsorbent; and (g) derivatized silica.
31. (canceled)
32. (canceled)
33. (canceled)
34. (canceled)
35. A method for extraction and desorption of one or more analytes
in an analyte-bearing sample, said method comprising: coating an
inner surface of a first cap with a sorptive coating; said sorptive
coating selected from the group consisting of: (a) an immobilized
polysiloxane polymer, having two attached functional groups,
wherein the first attached functional group is selected from the
group consisting of: alkyl, alkenyl, alkynyl, aryl, alkylaryl,
alkenylaryl, alkynylaryl, haloalkyl, and haloaryl, and the second
attached functional group is selected from the group consisting of:
alkyl, alkenyl, alkynyl, aryl, alkylaryl, alkenylaryl, alkynylaryl,
haloalkyl, and haloaryl; (b) a porous layer; (c) other immobilized
polymers above their glass transition temperature; (d) an
immobilized porous polymer; (e) a sol gel; (f) an immobilized
adsorbent; and (g) derivatized silica; attaching said first cap to
a first vessel containing said analyte-bearing sample; exposing
said sorptive coating to said analyte-bearing sample; agitating
said first vessel to expose said coating to said analyte-bearing
sample for a predetermined period of time; sorptively extracting at
least one analyte from said analyte-bearing sample; removing said
first cap from said first vessel; attaching a second cap to said
first vessel; attaching said first cap to a second vessel; said
second vessel containing a solvent; agitating said second vessel to
expose said analyte-bearing coating to said solvent; desorbing at
least one analyte from said analyte-bearing coating into said
solvent; and injecting said analyte-bearing solvent into an
analytical device.
36. A method for removing one or more contaminants present in an
analyte-bearing sample, said method comprising: coating an inner
surface of a first cap with a particulate coating; attaching said
first cap to a first vessel containing said analyte-bearing sample;
exposing said particulate coating to said analyte-bearing sample;
agitating said first vessel for a predetermined period of time;
removing said first cap from said first vessel; and attaching a
second cap to said first vessel.
37. The method of claim 36, wherein said particulate coating
comprises at least one selection of the group consisting of: (a)
molecular sieves; (b) activated alumina; (c) silica; (d) silica
gel; (e) ion exchange resins, and (f) desiccant.
38. (canceled)
39. (canceled)
40. (canceled)
41. (canceled)
42. The method of claim 37, wherein said second cap comprises a
selection from the group consisting of: an uncoated cap; and a
sorptive-coated cap.
43. The method of claim 42, wherein said sorptive-coated cap is
coated with a sorptive coating comprising at least one selection of
the group consisting of: (a) an immobilized polysiloxane polymer,
having two attached functional groups, wherein the first attached
functional group is selected from the group consisting of: alkyl,
alkenyl, alkynyl, aryl, alkylaryl, alkenylaryl, alkynylaryl,
haloalkyl, and haloaryl, and the second attached functional group
is selected from the group consisting of: alkyl, alkenyl, alkynyl,
aryl, alkylaryl, alkenylaryl, alkynylaryl, haloalkyl, and haloaryl;
(b) a porous layer; (c) other immobilized polymers above their
glass transition temperature; (d) an immobilized porous polymer;
(e) a sol gel; (f) an immobilized adsorbent; and (g) derivatized
silica.
44. The method of claim 43, further comprising: agitating said
first vessel to expose said sorptive coating to the analyte-bearing
sample for a predetermined period of time; sorptively extracting at
least one analyte from said analyte-bearing sample; removing said
second cap from said first vessel; attaching a third cap to said
first vessel; providing a second vessel containing a solvent;
attaching said second cap to said second vessel; agitating said
second vessel to expose said analyte-bearing coating to said
solvent; solvently desorbing at least one analyte from said
analyte-bearing coating; withdrawing an aliquot of analyte-bearing
solvent; and injecting said aliquot into an analytical device.
45. A method for performing purification, extraction, and
desorption of a sample, said method comprising: providing a first
vessel; coating the interior surface of said first vessel with a
first coating; providing a first cap; coating an interior surface
of said first cap with a second coating; pouring said sample into
said first vessel; attaching said first cap to said first vessel;
exposing said first coating and said second coating to said sample;
agitating said first vessel for a predetermined period of time;
sorptively extracting at least one analyte from said sample;
selectively removing at least one contaminant from said sample;
removing said first cap from said first vessel; attaching a second
cap to said first vessel; attaching said first cap to a second
vessel; said second vessel containing a solvent; agitating said
second vessel; solvently desorbing at least one analyte;
withdrawing an aliquot of analyte-bearing solvent; and injecting
said analyte-bearing solvent into an analytical device.
46. The method of claim 45, wherein said first coating is a
particulate coating comprising at least one selection from the
group consisting of: (a) molecular sieves; (b) activated alumina;
(c) silica; (d) silica gel; (e) ion exchange resins, and (f)
desiccant.
47. The method of claim 45, wherein said second coating is a
sorptive coating comprising at least one selection from the group
consisting of: (a) an immobilized polysiloxane polymer, having two
attached functional groups, wherein the first attached functional
group is selected from the group consisting of: alkyl, alkenyl,
alkynyl, aryl, alkylaryl, alkenylaryl, alkynylaryl, haloalkyl, and
haloaryl, and the second attached functional group is selected from
the group consisting of: alkyl, alkenyl, alkynyl, aryl, alkylaryl,
alkenylaryl, alkynylaryl, haloalkyl, and haloaryl; (b) a porous
layer; (c) other immobilized polymers above their glass transition
temperature; (d) an immobilized porous polymer; (e) a sol gel; (f)
an immobilized adsorbent; and (g) derivatized silica.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part under 37 CFR
1.53(b) to application Ser. No. 10/663,955, "Direct Vial Surface
Sorbent Micro Extraction Device and Method," filed on Sep. 16, 2003
by Robert Wohleb.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] This invention relates to the extraction of one or more
analytes by a sorption process. Specifically, this invention
relates to a device and method for performing direct vial
extraction and desorption. Additionally, this invention relates to
a device and method for direct vial purification.
[0005] 2. Description of the Related Art
[0006] To prepare samples for chemical analysis, often analytes, or
the compound of interest, must be separated from a sample matrix,
such as water, soil or animal tissue, and presented in a form
suitable for a particular piece of analytical equipment, such as a
gas or liquid chromatograph. There are various extraction methods
known and used to collect and prepare samples for such chemical
analysis. These methods include liquid/liquid extraction, solid
phase extraction, solid phase microextraction and stir-bar sorptive
extraction. The new trend in the industry is toward simplified
sample preparation that results in reduced waste and
pollutants.
[0007] Liquid/liquid extraction partitions an analyte between two
immiscible phases, such as an organic solvent and an aqueous phase.
When an aqueous phase contains the analyte it is extracted into the
immiscible organic solvent by placing the two phases into contact.
Extraction is enhanced by mixing. A relatively large volume of
solvent (typically greater than 100 mL) is necessary to carry out
the extraction. Partitioning of a compound between the solution
solvent and extractant solvent is governed by the distribution
constant, K, and the phase ratio, r. An example of such an
extraction would be EPA test method SW846 3510 which specifies that
one liter of aqueous sample should be serially extracted with 350
mL of methylene chloride. When the entire procedure is considered,
a total of 500 mL of solvent is used for each sample. The solvent
extract must be evaporated to reduce its volume to between 1 and 2
mL for placement into an autosampler vial prior to analysis.
[0008] Solid phase extraction (SPE) is often used to extract a
sample prior to analysis by chromatography. SPE uses silica
particles with an organic layer covalently attached to the surface
of the particles. The silica particles are packed into a tube or
disc, such as a polyethylene syringe barrel. The sample is then
prepared and an analyte extracted by passing the sample through the
solid sorbent. The analyte is then desorbed from the SPE media by
solvent extraction. An example of such an extraction is EPA test
method SW846 3535 which utilizes one liter of sample but requires
approximately 50 mL of solvents. The solvent extract must be
evaporated to reduce its volume to between 1 and 2 mL for placement
into an autosampler vial prior to analysis.
[0009] It is known in the art to use a sorbent to extract an
analyte from a solution. The analyte is later extracted from the
sorbent by thermal desorption or by back extracting with a small
amount of organic solvent. Sorption materials are usually
homogenous, non-porous materials that are above their glass
transition point (T.sub.g) and in which the analyte can dissolve.
The sample may be removed for analysis by thermal desorption or
solvent extraction.
[0010] Solid phase microextraction (SPME) is an extraction
technique wherein a fiber is coated with a sorbent layer. The
coating may be a polysiloxane or other immobilized sorbent. The
fiber is immersed in a liquid or exposed to its headspace during
which time the analyte is retained. The fiber may then be inserted
into a gas chromatograph injection port for analysis where it is
thermally desorbed or may be back extracted with a suitable
solvent. SPME is not accepted for EPA test methods.
[0011] Stir-bar sorptive extraction (SBSE) is used primarily for
direct mode sampling. SBSE utilizes a thick sorbent coating on a
magnetic bar stirrer that stirs the sample for a predetermined
amount of time during which time the analyte partitions between the
stir-bar sorbent and the sample. After extraction, the stir-bar is
removed and the analyte is thermally desorbed to the injection port
of a gas chromatograph.
[0012] Additionally, a sample may contain contaminants that
interfere with analysis of the sample. Thus, it may be desirable to
purify the sample by removing the contaminants before attempting to
extract the analyte. SPE is commonly used to remove contaminants,
with a particulate material, such as silica, packed in the barrel.
As previously discussed, SPE requires large amounts of solvent and
particulate material.
[0013] Examples of the prior art follow:
[0014] U.S. Pat. No. 5,691,206, issued to Pawliszyn on Nov. 25,
1997 discloses a device for carrying out solid phase
microextraction. The device is a fiber, solid or hollow, contained
in a syringe. The syringe has a barrel, a plunger slidable within
the barrel and a hollow needle extending from the end of the barrel
opposite the plunger. The needle contains the fiber. When the
plunger is depressed, the fiber extends beyond a free end of the
needle and when the plunger is in a withdrawn position the fiber is
located within the needle. To collect a sample, the needle is
inserted through a septum in a bottle containing the sample and the
fiber is extended into the sample. After a predetermined amount of
time, the fiber is returned to the needle and the syringe is
withdrawn from the bottle. The sample is analyzed by inserting the
needle through a septum in a gas injection port of a gas
chromatograph and extending the fiber.
[0015] U.S. Pat. No. 5,565,622, issued to Murphy on Oct. 15, 1996
discloses a simplified method for solid phase extraction of
components of interest from a sample. A syringe is used in which
the inner surface of the cannula or needle is at least partially
coated with a stationary phase such that aspirating the sample into
the needle results in adsorption of the components of interest into
the stationary phase. Aspiration of a solvent may be employed for
removing the components of interest from the stationary phase for
direct injection into a chromatographic instrument, or the
components of interest may be removed by thermal desorption,
wherein the needle is placed in the injection port of the
chromatographic instrument and heated. Because adsorption occurs on
the inner surface of the needle, the components of interest are not
readily storable.
[0016] U.S. Pat. Application Pub. No. US 2002/0105923, applied for
by Malik, published on Oct. 17, 2002 discloses a method of
preconcentrating trace analytes by extracting polar and non-polar
analytes through a sol-gel coating. The sol-gel coating is either
disposed on the inner surface of the capillary tube or disposed
within the tube as a monolithic bed.
[0017] Canadian Pat. No. 2,280,418, issued to Forsyth on Feb. 12,
2001, discloses a technique for carrying out solid phase
microextraction of analytes contained within a liquid, solid or
other material. A fiber assembly is mounted in the headspace of a
gas-tight container. A coating is applied to the fiber assembly
based on selectivity of the coating towards at least one analyte
present in the sample. The fiber assembly is exposed either in
direct contact with the sample, or indirectly through contact with
the gas present in the headspace of the container. After exposure,
the analyte-containing fiber is then desorbed so the desired
analyte can be analyzed. There are two alternatives for desorption
under Forsyth. The coating must be removed from the fiber through
solvent swell. Once the coating has been removed, the coating is
placed in an autosampler vial containing a portion of solvent. The
coating is suspended in the solvent, which can result in
contamination and interference with the autosampler. Additionally,
while this method reduces the amount of solvent necessary in the
prior art, this method still requires a greater amount of solvent
than the present invention. Alternatively, the coating can be left
on the fiber and the fiber can be placed in the autosampler vial
with a portion of solvent. However, this method still presents
problems with autosampler contamination and operation.
[0018] An article entitled, "Headspace Sorptive Extraction (HSSE)"
was published on an unspecified date by Tienpont, B. et al. at
http://www.richrom.com/assets/CD23PDF/d43.pdf. The article
discloses a glass rod support coated with a sorptive coating and
suspended in the headspace of a closed container, which contains
the analyte-bearing sample. The glass rod remains suspended above
the analyte-bearing sample until equilibrium is reached. The glass
rod is then removed from the closed container and undergoes thermal
desorption.
[0019] Therefore, it would be an improvement in the art to have a
device in which the extraction may be performed and the analyte
conveniently and transportably stored for later analysis. It would
also be an improvement in the art to have a device that minimizes
labor and equipment necessary for extraction and desorption. It
would also be an improvement in the art to have a device in which
desorption may be performed easily, in which the amount of solvent
waste is reduced, and that minimizes interference with the
autosampler. Additionally, it would be an improvement in the art to
have a device that removes contaminants in a sample and reduces
waste and equipment. It would also be an improvement in the art to
have a device that performs both extraction and purification,
thereby further reducing waste and equipment.
BRIEF SUMMARY OF THE INVENTION
[0020] The present invention comprises a device and method for
extracting analytes and/or removing contaminants from a sample.
[0021] Accordingly, the objects of my invention are to provide,
inter alia, a solid phase extraction system that: [0022] minimizes
the amount of solvent used; [0023] minimizes the amount of labor
required; [0024] minimizes glassware; [0025] allows samples to be
archived; [0026] allows extraction or purification to be performed
at the sampling site rather than the laboratory, [0027] allows the
extract to be subjected to replicate analysis; [0028] allows the
use of gas or liquid chromatography autosamplers; [0029] allows the
use of disposable sample vials; [0030] has greater reproducibility
than solid phase micro extraction; [0031] eliminates interference
with gas or liquid chromatography autosamplers; [0032] reduces or
eliminates sample cross contamination; [0033] allows desorption of
the analyte; and [0034] does not require expensive thermal
desorption equipment.
[0035] This invention is a cap coated with either a sorptive
coating or a particulate coating, wherein the coated cap is placed
over an opening to a vessel containing a sample fluid. Upon
exposure to the sorptive coating, the desired analytes are
extracted from the sample. Similarly, upon exposure to the
particulate coating, the contaminants are removed from the sample.
The coated cap may be removed and replaced by an uncoated cap for
transportation or storage of the sample. The analyte is then
desorbed by attaching the sorptive-coated cap onto a vessel
containing a portion of solvent and agitating the vessel.
[0036] Additionally, the particulate-coated cap may be used in
conjunction with a sorption vial including a sorptive coating.
Alternatively, a sorptive-coated cap may be used in conjunction
with a particulate coated vial. When the sample comes in contact
with the sorptive and particulate coatings, the particulate coating
removes contaminants in the sample while the sorptive coating
extracts the desired analytes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a cross-sectional view of the inventive cap.
[0038] FIG. 2 is a cross-sectional view of a sample vessel.
[0039] FIG. 3 is a cross sectional view of the inventive cap with a
syringe-permeable membrane.
[0040] FIG. 4A is a cross-sectional view of a screw cap.
[0041] FIG. 4B is a cross-sectional view of a plug cap and sorption
vial.
[0042] FIG. 4C is a cross-sectional view of a snap cap and sorption
vial.
[0043] FIG. 4D is a cross sectional view of a crimp cap and
sorption vial.
[0044] FIG. 5 is a cross sectional view of a coated sorption
vial.
DESCRIPTION OF THE INVENTION
[0045] Referring to FIGS. 1-2, an embodiment of the inventive cap
is depicted as 300. Sidewall 301 and top cover 310 are integrally
formed and define the boundaries of cap 300. Sidewall 301 has
sidewall exterior surface 302 and sidewall interior surface 324.
Top cover 310 includes top cover exterior surface 312 and top cover
interior surface 313. Top cover 310 has a cover periphery 316,
which defines the boundary of top cover 310. Sidewall interior
surface 324 and top cover interior surface 313 define cavity 330.
Top interior surface 313 is coated with either a sorptive coating
or a particulate coating to create coated surface 322. Coated
surface 322 extends into cavity 330. Top cover 310 may be solid, or
may have a syringe-permeable orifice 319, as seen in FIG. 3.
[0046] Referring to FIG. 2, cap 300 is used to close vessel 100 at
neck 140. Vessel 100 is used to provide an analyte-bearing sample
105 from which the analytes are to be extracted. Vessel 100 is made
from a rigid, nonreactive material, such as silica glass. Vessel
100 may be of any type, including various forms of flasks and vials
known in the art. Vessel 100 defines enclosed chamber 110 wherein
sample 105 is held, neck 140, and at least one vessel opening 102
through which sample 105 enters vessel 100. Neck 140 defines
passageway 122. Opening 102 provides fluid communication from a
sample source (not shown), through passageway 122, and into chamber
110.
[0047] Neck 140 is configured so that cap 300 may attach to it and
prevent fluid escape from chamber 110. Cavity 330 receives neck
140, and sidewall 301 holds top cover 310 over vessel opening 102
in a position preventing fluid communication between passageway 122
and the area external vessel 100. When cap 300 is attached to
vessel 100, coated surface 322 faces chamber 110 of vessel 100.
[0048] Referring to FIG. 3, an alternative embodiment of cap 300 is
depicted. Syringe-permeable member 319 permits a needle (not shown)
to pass through top cover 310. Syringe permeable member 319 is
contiguously formed with top cover 310. Syringe permeable member
319 is semi-permeable and prevents fluid from escaping cap 300.
However, a sharp object (not shown), such as a syringe needle, can
pierce through syringe permeable member 319 and enter cavity
330.
[0049] Various means may be used for interface between cap 300 and
vessel 200. Cap 300 can be a screw-on type cap, a crimp cap, a
stopper that plugs into neck 260, or a snap-on cap.
[0050] Referring to FIGS. 4A and 5, sidewall 301 is attached around
cover periphery 316. In one embodiment, sidewall 301 extends from
top cover exterior surface 312, past coated surface 322 and on to
sidewall end 308 distal coated surface 322. At least one cap thread
306 is helically attached along the cap interior surface 320 of
sidewall 301. In this embodiment, cap 300 attaches to vessel 200.
Neck 260 has at least one neck thread 264 helically attached around
neck exterior surface 268. Cap thread 306 and neck thread 264
permit cap 300 to be rotationally connected to neck 260.
[0051] In another embodiment, as depicted in FIG. 4B, sidewall 301
extends from cover periphery 316 to lower periphery 328. Cover
periphery diameter 318 is larger than lower periphery diameter 329.
Thus, sidewall 301 tapers as sidewall 301 extends from cover
periphery 316, past coated surface 322, and on to lower periphery
328. Cover periphery diameter 318 is larger than neck interior
diameter 267, and lower periphery diameter 329 is smaller than neck
interior diameter 267. Therefore, lower periphery 328 inserts into
passageway 266 and top cover 310 is depressed until neck interior
surface 263 snugly retains sidewall 301 in an interference fit.
[0052] In yet another embodiment, as depicted in FIG. 4C, sidewall
301 extends from top surface 312, past coated surface 322 and on to
sidewall end 308 distal coated surface 322. Proximate sidewall end
308, sidewall 301 forms lip 304, which inwardly protrudes from cap
interior surface 320. In order for engagement between cap 300 and
neck 260, neck 260 provides rim 264. Cap 300 attachedly seals onto
vessel 200 when top surface 312 is depressed and lip 304 snaps over
rim 264.
[0053] In yet another embodiment, as depicted in FIG. 4D, side wall
301 extends from top surface 312, past coated surface 322 and on to
sidewall end 308 distal coated surface 322. At least one cap thread
306 is attached along cap interior surface 320 of sidewall 302 such
that cap thread 306 is ring-shaped and has a smaller thread
diameter 307 than sidewall diameter 303. To accommodate this
embodiment, vessel 200 may have neck thread 264 around neck 260
with a larger neck thread diameter 265 than neck exterior diameter
261.
[0054] Referring to FIG. 5, vessel 200 is defined by vial exterior
wall 215 and vial base 250. Vessel 200 has a cylindrically, shaped
interior wall 210 with a conically-shaped bottom surface 220.
Vessel 200 also has a vial neck 260 through which there is an
opening 262 to bottom surface 220. Bottom surface 220 is oriented
such that the vertex 224 of the conical bottom surface 220 is
proximate vial base 250 while the directrix 226 is contiguous with
interior wall 210. Either a sorptive coating or a particulate
coating is applied proximate the vertex 224 of interior wall 210.
Alternatively, vessel 200 can have a cylindrical interior wall 210
without a conical bottom surface. When vessel 200 has a cylindrical
interior wall 210, a coating may be applied at any point on
interior wall 210.
[0055] In one embodiment of the invention, a sorptive coating and
particulate coating are used in conjunction to extract analytes and
purify the sample, respectively. Referring to FIG. 5, coated
surface 222 is a particulate coating and is applied to interior
wall 210 of vessel 200. Referring to FIG. 1, coated surface 322 is
a sorptive coating and is applied to cap interior surface 320 of
cap 300. Sample 105 is introduced to vessel 200 via vial opening
262. Cap 300 is then attachedly engaged with vessel 200 by one of
the methods discussed above. Vessel 200 is agitated by a mechanical
shaker (not shown) for a predetermined period of time, exposing
analyte-bearing sample 105 to the particulate and sorptive
coatings. Sorptive coating 322 sorptively extracts at least one
analyte present in analyte-bearing sample 105, and particulate
coating 222 removes at least one contaminant present in
analyte-bearing sample 105. Cap 300 is removed and the remaining
analyte-bearing sample 105 in vessel 200 is either archived or
disposed. Cap 300 is then attached to a vessel 200, which is filled
with solvent. The second vessel 200 is agitated for a predetermined
period of time, allowing desorption to occur. After desorption, the
analyte-bearing solvent is ready for analysis.
[0056] Alternatively, coated surface 222 and coated surface 322 may
each contain a particulate coating or a sorptive coating, as
determined for a specific test.
[0057] In the preferred embodiment, the sorptive coating is a
hydrophobic coating, such as an immobilized polysiloxane, for
example polydimethylsiloxane (PDMS), which contains only methyl
functional groups. The name "siloxane" is based on the Si--O--Si
unit and has found acceptance in scientific nomenclature.
Polysiloxanes are polymers with repeating siloxane units. Each
repeating siloxane unit contains two functional groups attached
(e.g. dimethyl) which may, or may not, be of the same type of
functional group. A functional group is an atom or combination of
atoms which gives a polymer its distinctive and characteristic
chemistry. A polysiloxane of 50 repeating units would therefore
have 100 methyl groups, whereas a siloxane unit with two different
types of groups such as phenymethyl would have 50 of each "type" in
the polysiloxane.
[0058] It is known in the art that immobilized polysiloxanes that
contain other types of functional groups, may be used as sorbents.
These include immobilized polysiloxanes containing phenyl or
trifluoropropyl functional groups. Examples of these polysiloxanes
include diphenylsiloxane-dimethylsiloxane copolymers and
trifluoropropylmethylsiloxanes. For more selective sorption
applications the immobilized polysiloxane may contain other types
of functional groups including alkyl, alkenyl, alkynyl, aryl,
alkylaryl, alkenylaryl, alkylaryl, haloalkyl or haloaryl. A
polysiloxane may contain said types of functional groups in any
combination. The selection of the type of functional groups permits
the partitioning of a particular analyte or analyes from the sample
The polysiloxane coating may be a polymer, a copolymer or a
combination of polymers.
[0059] Alternatively, sorptive coating may be (1) a porous layer,
such as a derivatized etched surface, (2) other immobilized
polymers that are above their glass transition temperatures such as
polybutadiene, (3) an immobilized porous polymer, such as
divinylbenzene, ethyleneglycoldimethacrylate, and copolymers of
divinylbenzene and ethyleneglycoldimethacrylate, polyethyleneimine,
acrylonitrile, n-vinyl-2-pyrollidinone or 4-vinyl-pyridine, (4) a
sol gel or (5) an immobilized adsorbent such as graphatized carbon
black. Sorptive coating may be any one of the coatings described or
a combination of two or more of the alternative coatings.
Additionally, sorptive coating may be derivatized silica beads. The
silica beads are derivatized by octadecyl (C.sub.18), octyl
(C.sub.8), butyl (C.sub.4), sorbent quartenary amine (SAX),
benzenesulfonic acid (SCX), aminopropyl, cyano, phenyl or
carboxylic acid. The derivatized silica is immobilized by a fibrous
mesh, or any other mechanical means. The selection of the coating
or coatings by one skilled in the art is dependent upon the analyte
or analytes to be partitioned from sample.
[0060] Acceptable particulate coatings for use in purifying a
sample include molecular sieves, activated alumina, silica, silica
gel, and ion exchange resins. The selection of particulate coating
by one skilled in the art is dependent upon the contaminants
targeted and the analytes present in the sample.
[0061] The foregoing disclosure and description of the invention is
illustrative and explanatory thereof. Various changes in the
details of the illustrated construction may be made within the
scope of the appended claims without departing from the spirit of
the invention. The present invention should only be limited by the
following claims and their legal equivalents.
* * * * *
References