U.S. patent number 3,642,449 [Application Number 04/838,674] was granted by the patent office on 1972-02-15 for detector composition and method.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the Army. Invention is credited to Thaddeus J. Novak, Edward J. Poziomek.
United States Patent |
3,642,449 |
Novak , et al. |
February 15, 1972 |
DETECTOR COMPOSITION AND METHOD
Abstract
A colorimetric method and composition for detecting compounds
containing ogens or aldehyde groups comprising the steps of
contacting the compounds with an inert absorbent impregnated with a
detecting composition comprising an amine, heating the absorbent
with its contents and observing the visible color change in the
absorbent.
Inventors: |
Novak; Thaddeus J. (Edgewood,
MD), Poziomek; Edward J. (Bel Air, MD) |
Assignee: |
The United States of America as
represented by the Secretary of the Army (N/A)
|
Family
ID: |
25277769 |
Appl.
No.: |
04/838,674 |
Filed: |
July 2, 1969 |
Current U.S.
Class: |
436/104; 422/413;
422/86; 436/126 |
Current CPC
Class: |
G01N
31/22 (20130101); Y10T 436/196666 (20150115); Y10T
436/163333 (20150115) |
Current International
Class: |
G01N
31/22 (20060101); G01n 021/06 (); G01n
021/24 () |
Field of
Search: |
;23/230,232,253,254
;252/408 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wolk; Morris O.
Assistant Examiner: Serwin; R. E.
Claims
We claim:
1. A colorimetric method comprising the steps of passing a gaseous
sample selected from the group consisting of haloaldehydes,
haloaliphatics, halosilanes, halophosphates and aldehydes through a
container containing a mixture comprising an inert absorbent
impregnated with a composition containing a substantially dry
residue of an amine selected from the group consisting of
aliphatic, aromatic and heterocyclic amines, said sample contacting
said amines, heating the container and its contents between
110.degree. - 120.degree. C. producing a visible color band in the
absorbent.
2. The method according to claim 1, wherein the gaseous sample is
haloaldehydes, haloaliphatics, halosilanes, and halophosphates.
3. The method according to claim 2, wherein the amine is
aliphatic.
4. The method according to claim 2, wherein the amine is
aromatic.
5. The method according to claim 2, wherein the amine is
heterocyclic.
6. The method according to claim 1, wherein the gaseous sample is
an aldehyde.
7. The method according to claim 6, wherein the aldehyde is
propionaldehyde or n-butylaldehyde.
8. A method according to claim 1, wherein the absorbent is silica
gel, cationic alumina, anionic alumina or neutral alumina.
9. A method according to claim 1, wherein the amines are aniline,
N-methylaniline, N,N-dimethylaniline, 2,5-diethyoxyaniline,
o-anisidine, o-dianisidine hydrochloride, diethylamine,
cyclohexylamine, dicyclohexylamine, tricyclohexylamine, pyridine or
3-methyl-2-benzothiazolinone hydrazone hydrochloride.
10. A method according to claim 1, wherein the sample is selected
from the group consisting of trichloroacetic aldehyde,
dichloroacetaldehyde, dibromomethane, trimethylchlorosilane, carbon
tetrabromide, and 2,2-dichlorovinyl dimethylphosphate.
11. A method according to claim 1, wherein the absorbent is
impregnated with a composition comprising a substantially dry
residue of an amine and dibromomethane as an antimasking
compound.
12. A method according to claim 11, wherein the sample is
haloaldehydes of trichloroacetic aldehyde or dichloroacetaldehyde
and the amine is an aromatic amine.
13. The method according to claim 1, wherein the container is a
transparent tube.
Description
DEDICATORY CLAUSE
The invention described herein may be manufactured, used, and
licensed by or for the Government for governmental purposes without
the payment to us of any royalty thereon.
This invention is directed to a method of detecting aldehydes and
halogenated compounds of aliphatic hydrocarbons, aldehydes, silanes
or phosphates in their vapor state.
The object of this invention is the colorimetric detection of
.alpha.-haloaldehydes.
A further object of the invention is the detection of compounds
which do not interfere with the color signal for the
.alpha.-haloaldehydes.
The detection of chloroaldehydes has been reported by several
investigators. Fritz Feigl, Spot Tests in Organic Analysis, Sixth
Edition, Elsevier Publishing Company, New York, 1960, describes the
method of indicating the presence of trichloroacetic aldehyde by
boiling the test sample in aqueous alkali containing pyridine, page
327, or saponifying the aldehyde in a phenol with subsequent
condensation with hydrazine, page 355.
In view that there are no simple vapor detecting systems for the
.alpha.-haloaldehydes, an investigation was instituted for
demonstrating the presence of the aldehydes which are known air
pollutants and may cause fatal lung injury.
As a result of our investigation it is now possible to detect
.alpha.-haloaldehydes of trichloroacetic aldehyde or
dichloroacetaldehyde in the range of at least 5 .mu.g. in the
presence of a detector amine selected from the group consisting of
aliphatic, aromatic and heterocyclic amines. In addition, other
compounds which do not interfere with .alpha.-haloaldehydes
detection can be detected alone but at higher concentrations based
upon their vapor pressure, that is, these compounds possess
relatively higher vapor pressures than the .alpha.-haloaldehydes.
These noninterfering compounds include C.sub.3 to C.sub.4
aldehydes, propionaldehyde, n-butylaldehyde, halogenated aliphatic
hydrocarbons, silanes or phosphates, for example dibromomethane,
carbon tetrabromide, trimethylchlorosilane, 2,2-dichlorovinyl
dimethylphosphate. The relative strength of the detecting signal
based on the compounds is strong for .alpha.-haloaldehydes, medium
for propionaldehyde and weak for the remaining compounds.
The various absorbents that may be employed in this invention are
silica gel (28-100 mesh), silica gel powder, and alumina for
chromatography (aneonic, cationic or neutral) taught by Brockmann
and Schodder, Chem. Ber, Vol. 74, page 73, 1941.
The use of silica gel tubes and the detecting apparatus are well
established in the open literature that may be employed according
to our colorimetric methods, Shepard, Anal. Chem., 19, 77, 1947;
Williams et al., Anal. Chem., 34, 255, 1962; Crabtree et al.,
Talanta, 14, 857, 1967.
In general the detecting tube containing the detecting mixture is
constructed as follows: A glass tube about 4 inches in length 2.5
to 3.0 mm. i.d. containing the mixture which is placed between
organdy plugs and then sealing off the glass ends. The filling
operation is conventional in the art such as tamping the detecting
mixture into the glass tube. Prior to using the filled tube, each
sealed end of the tube is broken off and inserted into the sampling
apparatus.
The detecting composition for the compounds described in this
invention is a mixture comprising about 0.075 to 0.125 g. of an
amine and 0.75 to 1.25 g. of an absorbent with subsequent air
drying of the mixture. About 0.1 g. of the mixture is placed in the
glass tube with proper sealing until the tube is required for use.
The impregnation of the absorbent with an amine can be facilitated
if desired by mixing the amine with a diluent prior to contacting
the absorbent. The diluent may be diethyl ether or ligroin which is
a volatile fraction of petroleum boiling in the range of 20.degree.
- 135.degree. C.
The apparatus we employed for indicating the presence of the
various compounds is disclosed by Crabtree et al., Talanta, 14, 857
(1967). The apparatus can be assembled from equipment readily
available in the laboratory. In the following description, the
lettered components correspond to the same component in the
apparatus description in the aforementioned Talanta publication. A
2.times.9 cm. test tube B, with a capacity of about 12 ml. is
fitted with 19/38 standard taper joint with an adopter C,
supporting a sidearm air inlet A, length of glass tubing extending
to about 5 to 10 mm. from the bottom of test tube. The glass tube
D, containing detector mixture was connected by a short length of
rubber tubing to the upper end of the glass tubing. The air sample
through the air inlet is drawn through the detector mixture by
compressing a rubber bulb E, fitted with a one-way valve. In the
alternative the sample containing the compound is placed in the
bottom of the test tube and air is taken in, by means of the bulb,
passing over the sample and the vapors are entrapped in the
detecting mixture. The tube is removed and heated in an oven at
110.degree. - 120.degree. C. in accordance with this invention.
The only requirement imposed on the sample is that the compounds be
readily vaporizable.
There is a decrease in the sensitivity in the colorimetric
determination of the chloroaldehydes resulting from the color
masking effect of the aromatic amines. We found that this masking
effect can be markedly diminished upon the addition of an equal
proportion of dibromomethane, based on the amine, to the aromatic
amines in preparing the detector mixture. There is an increase in
sensitivity by at least a factor of 3 in view of the fact that the
chloroaldehydes can be demonstrated in an amount of 5 .mu.g. as
distinguished from 15 .mu.g. in the absence of the dibromomethane
functioning as an antimasking agent.
We found that the addition of dibromomethane to the detection
mixture comprising aliphatic amines did not produce any noticeable
increase in sensitivity. This is probably in part due to the fact
that there is not the high color masking effect of the oxidation
products of the aliphatic amines as compared with the oxidation
products of the aromatic amines.
Although the free base is preferred in the detection mixture, one
can employ the salt of the amine with the sacrifice of sensitivity
as illustrated in Example 1(c) of 5 .mu.g. o-anisidine and Example
2(c) of 25 .lambda.g. o-dianisidine HCl. This salt effect results
in inhibiting the oxidation of the amine.
We found substantially the same color detection signal between the
compounds on the various silica gels or alumina absorbents Table 1
sets forth the amine with its corresponding detection color of the
trichloroacetic aldehyde on the various absorbents.
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TABLE 1
Color of the Amine Detection Signal Aniline Dark Brown-green
N-Methylaniline Green-blue N,N-Dimethylaniline Green-blue
2,5-Diethoxyaniline Brown o-Anisidine Brown o-Dianisidine
hydrochloride Light green Diethylamine Brown Cyclohexylamine Yellow
Dicyclohexylamine Yellow Tricyclohexylamine Yellow Pyridine Yellow
3-Methyl-2-benzothiazolinone hydra- zone hydrochloride Yellow
__________________________________________________________________________
EXAMPLE 1
a. An air sample of 10 to 20 cc. containing 15 .mu.g. of
trichloroacetic aldehyde vapor was drawn through the air inlet arm
of the apparatus, previously described, and contacting the vapors
with about 0.1 g. of detecting mixture prepared from a composition
comprising 0.075 to 0.125 g. aniline and 0.75 to 1.25 g. of silica
gel (28-100 mesh) in the glass tube. The tube was removed and
heated in an oven at 120.degree. C. for about 10 minutes whereby
the silica gel turned a dark brown-green indicating the presence of
the trichloroacetic aldehyde.
Similar results were obtained in utilizing silica gel powder for
the 28-100 mesh silica gel.
b. The procedure in (a), supra, was repeated with the exception of
5 .mu.g. of trichloroacetic aldehyde and about 0.1 g. of detecting
mixture prepared from a composition comprising 0.75 to 0.125 g.
aniline, 0.075 to 0.125 g. dibromomethane and 0.75 to 1.25 g. of
silica gel (powder or 28 to 100 mesh). Upon heating the detecting
mixture, the silica gel turned brown-green color.
c. The procedure and proportions in (b), supra, was repeated with
the exception of substituting aromatic amine members selected from
the group consisting of N-methylaniline, N, N-dimethylaniline,
2,5-diethoxyaniline and o-anisidine for the aniline and giving rise
to similar results, that is, 5 .mu.g. of the trichloroacetic
aldehyde was demonstrated.
d. The procedure, proportions and components in (a), (b) or (c)
were repeated with the exception of substituting the alumina,
cationic, anionic or neutral, for the silica gel giving rise to
similar results in sensitivity and color of the detection signal
upon heating the detector mixture.
EXAMPLE 2
a. The procedure in Example 1(a), was repeated with the exception
of 25 .mu.g. of trichloroacetic aldehyde vapor and substituting
diethylamine for the aniline and giving rise to the detector
mixture turning brown upon after heating.
b. The procedure in (a), supra, was repeated with the exception of
utilizing a detector mixture comprising an amine and absorbent, the
amine is selected from the group consisting of o-dianisidine HC1,
cyclohexylamine, dicyclohexylamine, tricyclohexylamine, pyridine
and 3-methyl-2-benzothiazolinone hydrazone hydrochloride and the
absorbent is a member selected from the group consisting of anionic
alumina, cationic alumina and neutral alumina, giving rise to the
corresponding color detection signal.
EXAMPLE 3
The procedures and proportions in Example 1 (a to d) and Example 2
(a to b) were repeated with the substitution of
dichloroacetaldehyde for the trichloroacetaldehyde and giving rise
to the corresponding color signal.
EXAMPLE 4
a. The procedure in Example 1(a) was repeated with the exception of
the air sample saturated with trimethylchlorosilane for the
trichloroacetic aldehyde and giving rise to green color detection
signal.
b. The procedure in (a), supra, was repeated with the exception of
utilizing a detector mixture comprising an amine and absorbent, the
amine is selected from the group consisting of o-dianisidine HC1,
cyclohexylamine, dicyclohexylamine, tricyclohexylamine, pyridine
and 3-methyl-2-benzothiazolinone hydrazone hydrochloride and the
absorbent is a member selected from the group consisting of anionic
alumina, cationic alumina and neutral alumina, giving rise to the
corresponding color detection signal.
c. The procedure in (a) and (b), supra, was repeated with the
substitution of saturated air sample selected from the group
consisting of propionaldehyde, n-butylaldehyde, dibromomethane,
carbon tetrabromide, and 2,2-dichlorovinyl dimethylphosphate and
giving use to a corresponding color detection signal.
* * * * *