Mustard Gas in Air Sensitivity of Qualitative Tests and a Rough Quantitative Determination WILLIAM RIEMAN 111 School of Chemistry, Rutgers University, New Brunswick, Iv. J.
S
EVERAL methods for the qualitative detection of
PIP'-dichlorodiethyl sulfide (mustard gas) have been described in the literature. Some of these tests were designed for the examination of foods (6), and others for the analysis of soils (4). Although some papers deal specifically with the detection of mustard gas in air (1, Z), no data are recorded on the minimum concentration of mustard gas in air that can be detected by the several methods. In the event of an air raid in which mustard is used, i t would be very desirable to have ready a portable apparatus for the detection of mustard gas, and also to know the sensitivity of the test. A test of sufficient sensitivity would also be useful after the raid to check the effectiveness of the decontamination or the natural disappearance of the poison. For these reasons several of the more promising qualitative tests were investigated with regard to their sensitivity when applied to contaminated air.
The two streams of air were mixed in a T-tube and passed through the test solution contained in a Pyrex test tube, 10 em. long and 12 mm. in diameter, and fitted with a 2-hole rubber stopper. The delivery tube entered through one hole, extended almost to the bottom, and terminated in a constriction of 1-mm. internal diameter. The other hole held the exit tube which led the air through another mixture of charcoal and soda-lime. The connections between the mustard bubbler and the test tube were glass-to-glass joints covered with tight rubberotubing. The temperature of the laboratory was kept at about 20 .
TABLE 11. QUALITATIVE TESTS FOR MUSTARD GAS (Velocity of mixed stream was 170 ml. per minute in all casea.) Concentration of MusTotal Mustard in tard in Mixed Mixed Reagent Stream Time Stream Results r/ml. Min. Y Gr i gn ard 0.020 10 Negative 34 0.040 10 HAuCI, Very faint 68 0.040 20 HAuClr Faint 136 0.040 0-Kaphthol Faint 10 68 0,020 10 34 HAuC14 paper Xegative NazPtIB paper 0,020 10 34 Segative
Materials Used The mustard gas was prepared in this laboratory by William A. Raimond, and the fraction boiling between 115' and 116" C. a t 25 mm. was used. It froze sharply a t 14.5' C. Comparison of these figures with the recorded literature (6) indicates that the compound had a high degree of purity. I t was colorless and had only a faint odor of garlic. The Grignard reagent (KCuL), alcoholic p-naphthol, and iodolatinate solution were prepared according to the directions of tainsby and Taylor ( 6 ) . Filter paper was impregnated with iodoplatinate solution as recommended by Bradley ( 1 ) . -4 1 per cent solution of chlorauric acid ( 3 ) was prepared, and filter paper was impregnated with this solution. A solution of acetic acid, made by diluting 5 ml. of reagent grade acetic acid to 100 ml., and a 0.5 per cent solution of potato starch were prepared. A small quantity of mustard was accurately weighed and dissolved in sufficient glacial acetic acid to give a standard solution containing 0.10 mg. per ml.
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TABLEI. COLORIMETRIC DETERYIXATION O F MUSTARD GAS ABSORBEDBY ACETICACID Test No. 1 2 3 4 5 6
Velocity of Air Streams A B Ml./min. 1.8 0 1.7 170 170 1.7 3.4 170 170 3.4 170 3.4
Concentration of Mustard in Mixed Stream -y/ml.
1.0 0.010 0.010 0.020
0.020 0.020
Time Min. 5.5 10.0 5.0 10.0 5.0 2.5
Total Mustard in Mixed Stream Y
10 17 8.5
34
17 8.5
Mustard Absorbed
r
%
7.5
75
4
24 24 29 29 24
2 10 5 2
Apparatus
Procedure The velocity of stream A was usually 170 20 ml. per minute, the maximum velocity that could be used without risk of blowing the solution out of the test tube. I t also represents a convenient rate for a field test when the air is passed by means of a rubberbulb aspirator. The velocity of stream B was varied between 1.7 and 6.8 ml. per minute in order to vary the concentration of mustard vapor in the mixed air stream. For the iodoplatinate test, the air was bubbled through 1.0 ml. of 5 per cent acetic acid for the indicated length of time, then the test tube was removed from the apparatus, and one drop of iodoplatinate solution was added, followed by one drop of starch solution. The pink iodoplatinate turns blue if 2 micrograms or more of mustard are present. The mustard absorbed by the acetic acid can be determined with an accuracy of 1 microgram by comparing the intensity of the blue color with a series of standards. The color standards are prepared by putting 0.02, 0.04, 0.06, 0.08, and 0.10 ml. of the standard mustard solution in Pyrex test tubes (10 cm. by 12 mm.), diluting to 1.0 ml. with water, and adding iodoplatinate and starch solutions. The variation in the concentration of acetic acid does not appreciably affect the intensity of the blue color. The color standards must be prepared a t the same time that the color is developed in the unknown solution. The tests with the Grignard reagent and with chlorauric acid consisted merely in letting the air bubble through 1.0 ml. of the respective solutions and observing a t intervals whether a precipitate had been formed. The 8-naphthol test was done similarly, except that the test tube was surrounded by a water bath a t 40'. The tests with the impregnated papers were performed by putting the papers into the Pyrex test tube and passing the contaminated air stream through this tube. The iodoplatinate paper was moistened with water before use, but the chlorauric acid paper was used dry. f
The results of the colorimetric determination of mustard gas absorbed by the dilute acetic acid under various conditions are summarized in Table I. The values in column 4 were calculated from the vapor pressure of mustard (5)on the
The apparatus was essentially like that of Yablick, Perrott, and Furman ( 7 ) . A stream of air, denoted as A , from a compressor was purified by passage through a mixture of soda-lime and charcoal. The velocity of this stream was controlled by a pinchcock and pressure regulator and was measured by a flowmeter. A second stream of air, B, was similarly purified, controlled, and measured and mas then bubbled through a vessel containing mustard liquid immersed in a water bath maintained at 20 * 1" C.
that the air in
was saturated with the
vapor- hfost of the entries in column 7 are the mean of duplicate determinations. 411
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INDUSTRIAL AND ENGINEERING CHEMISTRY
The results of the qualitative tests for mustard gas are given in Table 11.
Discussion Test 1 reveals that the absorption of the mustard vapor b y the dilute acetic acid is nearlycomplete when the air veiocity is small. Tests 2 to 6 indicate that the absorption is much less complete when the velocity is increased. Nevertheless, mustard vapor can be detected by the iodoplatinate method under the recommended conditions with a 5-minute absorption period when its concentration is only 0.01 microgram per ml. (test 3). Since this concentration requires a n exposure of 2.5 hours for fatal results (3), the iodoplatinate method is fairly satisfactory for detecting dangerous concentrations of mustard vapor. It is stated (6) that this test
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is not applicable in the presence of oxidizing agents such as chlorine or nitrous fumes or in the presence of reducing agents, including the arsenical vesicants in large concentration. Table I1 reveals that the other tests are much less sensitive than the test with iodoplatinate solution.
Literature Cited (1)
(2)
(3)
(4) (5) (6)
(7)
Bradley, T. F., C h a . Eng. News, 20, 893 (1942). Cox, H. E., A n a l y s t , 64, 807 (1939). England, Department of Air Raid Precautions, "Detection and Identification of War Gases", Brooklyn, N. Y., Chemical Publishing Co., 1940. Hoogeveen, A. P. G., Chemistry and I n d u s t r y , 59, 550 (1940). Jackson, K. E., Chem. Rev., 15,425 (1934). Stainsby, W. J., and Taylor, A. McM.,Analyst, 66, 44 (1941). Yablick, M., Perrott, G . St. J., and Furman, N. H., J. Am. Chem. Soc., 42, 266 (1920).
Microdetermination of Magnesium with the
Polarograph CHRISTOPHER CARRUTHERS T h e Barnard Free Skin and Cancer Hospital and Washington University, S t . Louis, Mo.
A polarographic procedure is given for the determination of microquantities of magnesium as the hydroxyquinolate.
I
NVESTIGATION of possible chemical changes produced in mouse epidermis b y methylcholanthrene (1) requires special microprocedures, because of the small amounts of tissue available for analysis. Magnesium, for example, cannot be determined by any ordinary technique, and even polarographic determination is not practical. This metal gives a very poorly defined wave in solutions of tetramethylammonium salts as the supporting electrolyte (3, 8). Muller (8) and Heyrovsk? and Berezicky (2) attribute the pronounced maximum, and the ensuing large diffusion current, to the evolution of hydrogen resulting from the rapid decomposition of water a t the magnesium-mercury amalgam which is formed. Since 8-hydroxyquinoline has proved to be of great value for the determination of magnesium (11); a method for the reduction of magnesium based upon the polarographic reduction of 8-hydroxyquinoline was devised. The author found that this latter compound is reduced a t the dropping mercury electrode and that the diffusion current is proportional to the concentration. It was therefore possible to devise a polarographic procedure for the microdetermination of magnesium.
Apparatus and Reagents Heyrovskj. polarograph, Model XI (E. H. Sargent Bi Co.). A phosphate buffer mixture of pH 7.6, 3.33 M with respect to both disodium phosphate and monopotassium phosphate. A wash solution made by saturating 95 per cent alcohol with magnesium hydroxyquinolate and filtering just before use through a sintered-glass filter covered with a layer of asbestos. Solution A, prepared by diluting 2 ml. of 1 per cent gelatin (E.astman's de-ashed) solution and 30 ml. of 0.1 iV hydrochloric acid to 100 ml. with the phosphate buffer solution.
Solution B, prepared by diluting 2.7 ml. of 1 per cent gelatin solution to 100 ml. with the phosphate buffer. Solutions A and B should be made just before use or stored in a refrigerator, as the presence of gelatin can favor a rapid growth of microorganisms.
Procedure The investigations of Redman and Bright (9) and of Miller and McLennon (6) have shown that the quantitative precipitation of magnesium hydroxyquinolate is very critical and much affected by the conditions under which i t is carried out. For calibrationpurposes, the author found that toprevent high results i t was necessary to precipitate the magnesium hydroxyquinolate by the method of Kolthoff and Furman (4) as follows: A solution of magnesium chloride (made by dissolving magnesium ribbon in hydrochloric acid) is treated with ammonium chloride and ammonium hydroxide and then heated to 96 ' to 100" C. To this a 5 per cent alcoholic solution of S-hydroxyquinoline (Eastman) is slowly added with stirring until a slight excess is present. Digestion is continued for a few minutes and the solution is then filtered hot through a sintered-glass filter, After the precipitate has been washed thoroughly with water followed by alcohol, it is dried at 105" C. overnight. The calibration data (Table I) were obtained by dissolving 400 mg. of the magnesium hydroxyquinolate in a beaker with 150 ml. of 0.1 - \ I hydrochloric acid and transferring this solution quantitatively to a 500-ml. glass-stoppered volumetric flask by rinsing the beaker several times with the phosphate buffer solution. The flask was made to volume with this same buffer solution after the addition of 10 ml. of 1 per cent gelatin. This 2.29 x 10-3 M stock solution (nearly saturated) was diluted in 100ml. glass-stoppered volumetric flasks to give magnesium hydroxyM. Proportionate quinolate solutions 1.837 to 0.1148 X amounts of 0.1 A' hydrochloric acid, 1 per cent gelatin, and phoshate buffer were added t o maintain a constant pH and equivaPent gelatin concentrations. The importance of pH in the reduction of organic compounds has been stressed by Miiller ( 7 ) and by Kolthoff and Lingane (6). Solutions in Table I had a pH of 7.09 to 7.12 (glass electrode). Solution A was used for measuring the residual current, i,.
