Two New Sensitive Spot Tests for the Detection of Thiodiphenylamine FRITZ FEIGL and DORA HAGUENAUER-CASTRO laboratorio da ProduFao Mineral, Ministirio da Agricultura, Rio de Janeiro, Brazil (Translated by RALPH E. OESPER, University of Cincinnati)
b Ethylene blue results if alcohol solutions of thiodiphenylamine (phenothiazine), iodine, and diethylamine are brought together. A violet product (probably a thiazine dyestuff) is formed if a water solution of chloramine-T is brought into contact with solid thiodiphenylamine or with its solution in an organic liquid. These color reactions can serve as bases for tests for thiodiphenylamine. The identification limits are in the range 0.03 to 0.6 pg. Oxidation products of phenothiazine and some of its derivatives also yield positive tests.
H
T
is important with respect to insecticides, pharmaceutical preparations] and for medical and veterinary uses. Recently, Gunew (2) described a procedure for determining thiodiphenylamine in 25to 35-mg. quantities. The method is based on the weight and melting point of the compound after it has been isolated by chromatography. However, that method and the colorimetric bromide method (1) as well as others in the literature are not truly specific chemical methods for detection of the compound. In view of the importance of thiodiphenylamine it seemed worthwhile to search for specific or a t least selective reactions which might be of value in its microanalytical chemistry. Two rapid, sensitive color reactions suitable for its spot test detection are d e scribed. Preliminary study shows that these reactions may lend themselves well to colorimetric and chromatographic determinations. HIODIPHENYLAMINE
ETHYLENE BLUE METHOD
Kehrmann (3) described a straightforward procedure for the preparation of methylene blue based on the reaction of thiodiphenylamine with bromine and excess dimethylamine in alcoholic solution. The initial product (Equation l) is the polybromide of phenazthionium base, which then yields the bromide of methylene blue through oxidative condensation (Equation 2) with dimethylamine: 14 1 2
ANALYTICAL CHEMISTRY
+ Br- + 4HBr
(2)
Attempts to adapt this method for analytical use showed that the Kehrmann procedure could be modified advantageously by using iodine and diethylamine. Analogous reactions then occur with formation of ethylene blue. The excess of iodine is easily removed by means of sodium sulfite. . A drop of the alcoholic test solution is treated in a micro test tube with 1 drop of 0.5% alcoholic iodine solution followed by l drop of a 1% solution of diethylamine in alcohol. The mixture is allowed to stand a t room temperature for 1 minute and then a pinch (tip of knife blade) of solid sodium sulfite is added. The test tube is placed in boiling water until (around 2 minutes) a comparison mixture containing no diethylamine becomes colorless. If the response is positive, a blue color develops whose intensity is dependent upon the quantity of thiodiphenylamine present. Limit of identification, 0.5 ,pg. of thiodiphenylamine. Procedure.
CHLORAMINE-T METHOD
If solid chloramine-T (sodium N chloro-p-toluenesulfonamide) is added to an alcoholic solution of thiodiphenylamine, a violet product appears a t once. After dilution with water, this colored material can be extracted by ether, benzene, chloroform, or carbon disul-
fide. Likewise, if a benzene solution of thiodiphenylamine is added to a concentrated aqueous solution of chloramine-T and shaken, the benzene layer becomes violet and the water layer colorless. When solid thiodiphenylamine is moistened with aqueous chloramine-T solution, the solid turns violet. The chemistry of the color reactions cannot be stated with certainty as yet, because the colored product has not been isolated in analyzable pure form. However, it must not be conjectured that the hypochlorite split out of the chloramine-T by hydrolysis brings about an oxidation of the thiodiphenylamine to the base analogous to Equation l . If this were the case, the color reaction would be brought about also by bromine water and N-bromo(chloro)succinimide which yield BrO- or C10ions in aqueous solution. Since this does not occur, it is very likely that the two compounds produced by the hydrolysis of the chloramine-T: CHa
-0 S02NClNa +
-
Ha0 +
+
CH~Cd&S02NH~NaClO (3) c
NHzSOpR
react with thiodiphenylamine. The following redox- and oxidative condensation reactions seem plausible for the formation of thiazine dyes:
()[)3+ H
+
2NH2S02R 3NaC10+
0”)3+ +
OH-
\&/
RS02HN’
NHSOnR
2H20
a:)3+ H
NHtS02R
n””Yi+
OH-
+ 3NaCl
(4)
+ 2NaC10
-P
+ H2O + 2NaCI (5)
This assumption is in agreement with the finding that a color reaction (red violet) also occurs in acid solution and that the resulting colored products, like other thiazine dyes, can be extracted from aqueous solution or suspension with ether or benzene. The detection with chloramine -T can be accomplished with alcoholic solutions of thiodiphenylamine by Procedure I or with the benzene solution by Procedure I1 or 111. Procedure I. A drop of the alcoholic test solution is placed in a micro test tube and several milligrams of chloramine-T are added. A blue-violet color appears a t once, the intensity increasing with the quantity of thiodiphenylamine present. Limit of identification, 0.6 pg. Procedure 11. Several drops of a freshly prepared 10% water solution
of chloramine-T are placed in a micro test tube and 1 drop of the benzene solution of the test material is added. The test tube is then placed in a water bath preheated to 60" to 70" C. The benzene layer becomes violet if the response is positive. The color deepens on extrxtion. Limit of identification, 0.05 pg. Procedure 111. A drop of the ether or benzene test solution is placed on filter paper and as soon as the solvent has evaporated, the area is spotted with 1 drop of a freshly prepared 10% aqueous solution of chloramineT. Depending on the amount of thiodiphenylamine present, a violet stain or ring appears within 1 to 2 minutes. Limit of identification, 0.03 pg. Thehigh sensitivity attainable with Procedure I11 points up the advantage of color reactions on filter paper, thanks to the retention of the reagents
and the reaction products in the plane of the paper. The color reaction described here likewise permits a new and very sensitive test for chloramine-T and other sulfohaloamides. A report on this additional application of the reaction will appear later. ACKNOWLEDGMENT
The authors thank the Conselho Nacional de Pesquisas for financial support. LITERATURE CITED
(1) Association of Official Agricultural Chemists, Washington, "Official Methods of Analysis," 8th ed., . 679, 1955. (2) Gunew, D., Analyst 85, E60 (1960). (3) Kehrmann. F., Ber., 49, 3832 (1916). RECEIVEDfor review March 6, 1961. Accepted June 18, 1961.
Spectrophotometric Determination of Olefins A. P. ALTSHULLER and S. F. SLEVA Roberf A. Taff Sanitary Engineering Center, 4676 Columbia Parkway, Cincinnati 26, Ohio
b Four-carbon and higher molecular weight olefins can be determined quantitatively in the gas and liquid phases by reaction with p-dimethylaminobenzaldehyde in concentrated sulfuric acid, under appropriate conditions, and measurement of the absorbance at 500 mp. With gaseous olefins the absorptivities are such that 0.1 p.p.m. or less can be determined. Interference by formaldehyde and excess aromatic hydrocarbons and phenols is appreciable, and simple methods for their removal are discussed. The method has been applied to the analysis of automobile exhaust and diluted irradiated exhaust mixtures. Liquid olefins have been studied under somewhat different reaction conditions; consequently, the positions, shapes, and intensities of the absorption bands differ somewhat. Although the work on liquid olefins was not as extensive as in the investigation of olefin gases, the results should have applicability in the identification and analysis of small quantities of liquid olefins.
M
OST chemical methods have lacked
sufficient sensitivity for convenient trace analysis of atmospheric concentrations of olefins (2, 3, 10, 11). Certain other limitations have existed in terms of interferences, variation in response of individual olefins, siqplicity, and ease of application.
Previous workers have studied in some detail the color reactions between aromatic aldehydes and alcohols in concentrated sulfuric or hydrochloric acid (Komarowsky reaction). Both dehydration (6, 9 ) and aldol condensation ('7) have been suggested as steps in the reaction. It seemed possible, as suggested (Q),that the alcohols and olefins react with the aromatic aldehyde through similar intermediate species. Preliminary measurements on the reaction products of olefins with a number of aromatic aldehydes in concentrated sulfuric acid indicated that p-dimethylaminobenzaldehyde is a very satisfactory reagent and it was subsequently used. When p-dimethylaminobenzaldehyde reacts with olefins in concentrated sulfuric acid under appropriate conditions, colored products are obtained which usually have their absorption maxima or shoulders a t 500 mp. The present colorimetric method for olefins is more sensitive than the previous ones. Gaseous olefin concentrations down to about 0.1 p.p.m. by volume and liquid olefin concentrations of 1 pg. per ml. can be determined quantitatively, using reasonable sampling periods. The experimental procedure is simple and rapid. The colored product formed is stable for several hours. The new method is particularly applicable to the analysis of total gaseous four-carbon and higher molecular weight olefins, and to liquid
mixtures of olefins with other aliphatic materials. GASEOUS AND VAPOR STATE
OLEFINS EXPERIMENTAL
The sources and purities of the olefins used, possible interferences, and the preparation of olefins in sulfuric acid solution have been discussed (3). In the bulk of the work done, individual hydrocarbons and mixtures of hydrocarbons were introduced into aluminized Scotchpak or Mylar bags by microsyringes and diluted (20 to 100 liters) (4). The gaseous hydrocarbon samples were injected from a microsyringe through a septum cap on a glass T and flushed into the bag with air. Liquid samples were injected from microsyringes through a septum cap on a glass T into an evacuated cylindrical flask, and the vapor in the flask and associated glass tubing then was flushed into the bag with air. For the liquid samples 1and 10-pg. microsyringes were used; for gas samples 10-ml. and 30-pl. syringes were used. The gas or vapor mixtures in air had hydrocarbon concentrations ranging from 0.2 to 500 p.p.m. by volume in total volumes ranging from 20 to 150 liters. Diffusion cells were used to obtain trace concentrations of the vapors of formaldehyde and of 1hexene in air (1). p - Dimethylaminobenzaldehyde (DAB) is prepared by dissolving 10% by weight of DAB (m.p. 73-75') in VOL. 33, NO. 10, SEPTEMBER 1961
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