Thomas (IS) claims that as much as 5 p.p.m. of sulfur dioxide does not
interfere with the determinations of concentrations of nitrogen dioxide of the order of 0.4 to 0.7 p.p.m. with this device. Neither Cholak and his coworkers (2) nor Moore, Cole, and Katz (IO) reported this interference. The present work concludes that concentrations of sulfur dioxide of the order of 0.2 to 1.0 pap.m. and higher bleach the color of the dye formed with the mixed reagent when it is used as the trapping agent. This bleaching may not be apparent in the relatively high concentrations of nitrogen dioxide used by Thomas in his experiments (the concentrations are 5 to 10 times that normally present in New York City’s atmosphere). This method is empirical because of the dismutation of the nitrogen dioxide-nitrogen tetroxide mixture and because of the need for standardization of the absorbers. The quantitative aspects of the dismutation of nitrogen dioxide-nitrogen tetroxide absorbed in aqueous solution are not entirely known. Patty and Petty (11) found that the apparent average recovery of nitrite from nitrogen dioxide-nitrogen tetroxide mixtures (on the assumption that 1 mole of NOz gas yields 1 mole of NO2 ion) was 57 f 2.6y0. Their maximum and minimum recoveries -were 65 and
52%, respectively. Others on this basis reported nitrite recovery of the The actual order of 72% (18). amount of nitrogen dioxide in the air is probably greater than the results reported because only 60 to 70% of the nitrogen dioxide-nitrogen tetroxide mixture is converted to nitrite and only that portion is measured. If all of the nitrogen dioxide absorbed were converted to nitrate, the total amount could be determined by either the phenoldisulfonic acid or xylenol method (5, 8). Although such methods are far more tedious, the authors are investigating them. LITERATURE CITED
Bratton, A. C., Marshall, E. K., J . Biol. Chem. 128,537 (1939). Cholak, J., Schafer, L. J., Yeager, D. Younker, W. J., “Gaseous Contaminants in the Atmosphere,” 130th Meeting, ACS, Atlantic City, N. J., September 1956. Dept. Sei. Ind. Research Brit., Leaflet 5 (1939). Elliott, hl. A., Nebel, G. J., Rounds, F. G.. Air Pollution Control h S O C . ’ Annual Meeting, Paper 55-19, May 1955. ( 5 ) Goldman, F. H . , Jacobs, M. B., “Chemic$! Methods in Industrial Hvgiene, Interscience, New York,
1953. (6) Greenburg, L., Jacobs, M. B., Znd. Eng. Chem. 48, 1517 (1956). (7) Greenburg, L., Smith, G. W., U. S.
Bur. Mines, Rept. Invest., 2392
(1922). (8) Jacobs, .M. B., “War Gases-Their
Identification and Decontamination,” Interscience, New York, 1942; “Rapid Method for Nitrogen Dioxide-Nitrogen Tetroxide in Atmosphere,” Metropolitan N, Y. Section, Am. Ind. Hyg. Assoc. meeting, May 1945; “The Analytical Chemistry of Industrial Poisons, Hazards, and Solvents,” Interscience, New York, 1949: “Chemical Analxsis of Foods and Food Products, Van Nostrand, New York, 1951. (9) Magill, P. L., Littman, F. E., Am. SOC. Mech. Engrs., Paper
53-A-163 (1953). (10) Moore, G. E., Cole, A. F. W.,
Katz, M., “Concurrent Determination of Sulfur Dioxide and Nitrogen Dioxide in the Atmosphere,” Air Pollution Control Assoc. meeting, Buffalo, N. I-., May 1956. (11) Patty, F. A., Petty, G. M., J . Znd. Hyg. Toxicol. 25, 361 (1943). (12) Saltzman, B. E., ANAL. CHEM.26, 1949 (1954). (13) Thomas, M. D., MacLeod, J. A . ,
Robbins, R. C., Goettelman, R. C., Eldridge, R. W., Rogers, L. H.,Zbid., 28,1810( 1956). (14) Wilson, W. L. “An Automatic Impinger for Air Sampling,” .Air Pollution Control Assoc. meeting, Chattanooga, Tenn., May 1954. RECEIVEDfor review March 28, 1957. Accepted September 26, 1957. Meetingin-Miniature, Metropolitan Long Island Subsection, New York Section, ACS, Brooklyn, N. Y., February 15, 1957.
Rapid Quantitative Determination of Sulfur in Organic Compounds IHOR LYSYJ and JOHN E. ZAREMBO Central Research, Chemical Divisions, Food Machinery & Chemical Corp., Princefon, ,An investigation was made to determine sulfur in organic compounds without cumbersome and expensive equipment, and to reduce the time involved in elemental analyses. The materials examined include compounds containing as much as 50% sulfur. The precision of the method is to & l % and a single analysis requires approximately 25 minutes of actual working time.
A
of time-honored and dependable methods for determination of sulfur in organic compounds are based on Carius digestion (1-5, 14, I 6 ) , Pregl combustion (3, 7, IO), Parr bomb combustion (8, 9, IS, I 6 ) , and eventual determination of sulfate by volumetric or gravimetric methods. However, these methods possess inherent diffiNUMBER
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ANALYTICAL CHEMISTRY
N. J.
culties-Le., they are time-consuming, require considerable manipulation, and can be executed only with specialized and expensive equipment. T o eliminate these difficulties and to meet the ever-increasing volume of work in industrial and research analytical laboratories, a quest was made for a rapid, precise, simple, and economical method of elemental analysis. Following the techniques of Mikl and Pech (6), Schoniger (11, 18) developed a method for the combustion of organic materials in a n Erlenmeyer flask filled with oxygen. H e also suggested a n acidimetric determination of sulfur in compounds containing carbon, hydrogen, oxygen, and sulfur following such combustion. The authors investigated this type of combustion, followed by simple acidimetric titration of sulfuric acid.
The apparatus developed consists of a 500-ml. iodine or Erlenmeyer flask and a ground-glass tube, 24/40, whose lower end is closed and into which is sealed a platinum spiral. The upper portion of this tube is used as a handle and the platinum spiral serves as the sample carrier during the combustion. The sample is weighed on a small piece of filter paper or into a gelatin capsule. The paper is then folded and inserted into the platinum spiral. The gelatin capsule is simply fitted into the spiral. T o each is attached a small filter paper wick. The wick is ignited with a sma!l Bunsen burner and the whole unit IS inserted into a n iodine flask which has been flushed with oxygen and contains a solution of hydrogen peroxide. The reaction takes place in about 30 seconds:
The sulfur dioxide and sulfur trioxide combine with hydrogen peroxide to form siilfuric acid: SOI
+ Sot + Ha02 + H,O
-
2 H$O,
(2)
The piece of filter paper containing the solid sample is bent in half and then folded carefully into a small roll to fit into the platinum spiral and still have a free end 5 to 6 em. long for
The excess hydrogen peroxide and carbon dioxide are removed by boiling the solution, and the sulfuric acid is titrated with 0.02N sodium hydroxide, with methyl red as an indicator. There is no interference from carbon dioxide after this treatment of the sample. The percentage of sulfur is determined from the titer of the alkali. Variations in reaction conditions produce inaccurate results. Attempts to accelerate the conversion of sulfur dioxide to sulfur trioxide were made by investimtina the effectiveness of several concenirati& of hydrogen p e r o x i d e ea.. 3. 6, 15. 30, 60,and 90%. With concentrations of hydrogen -peroxide above 6% methyl red indicator undergoes oxidation and does not give a good end point, and a long period of time is required to drive off the excess. The choice of a 6% solution was justified by the very efficient conversion of sulfur dioxide to sulfur trioxide and the relative ease of eliminating the excess. Experiments have demonstrated that under the conditions of the method, sulfur in organic compounds containing carbon, hydrogen, oxygen, and sulfur may be determined. Nitrogen, halogens, phosphorus, or metals interfere with the alkalimetric titration procedure. In the presence of these elements, the resulting sulfate is determined by a gravimetric method.
Figure 1.
Combustion apparatus
Table I.
igniting the sample. The sample is then fitted into the helices of the platinum spiral, with the fuse extending vertically away from the widest bend of the wire. To a 500-ml. iodine flask, 50 ml. of 6% hydrogen peroxide solution and 2 drops of methyl red indicator are added; then the solution is neutralized by adding 1 to 2 drops of 0.0200A’ sodium hydroxide until a yellow color is obtained. The flask is then flushed with oxygen, by allowing a slow stream of oxygen gas to pass through a small piece of rubber tubing extending a few centimeters from the surface of the solution for about 1minute. After this time, with the gas still passing into the flask, the filter paper fuse is lighted and allowed to burn until the flame is approximately 1 em. from the sample. The rubber tubing is rapidly removed from the flask and the sample is quickly inserted into the flask and closed by the ground-glass unit containing the sample and spiral. The tube is held in this position until the burning is complete. When the sample is placed in the oxygen atmosphere, it burns rapidly and completely in ahout 20 seconds. As soon as the sample has burned completely, the flask is shaken vigor-
Determination of Sulfur Parr Bomb, Proposed Procedure, Gravimetric, % % Theory Sulfur Recovery Sulfur Recovery Procedure I
% S,
Sample Dioctenyl disulfide
22.38
22.77
101.74
3-Sulfolene
27.14
26.79
98. 85
Dioctenyl trisulfide
30.19
29.98
99.30
Dioctenyl tetrasulfide
36.58
36.04
98.53
47.07
47.10
34.05
34.22
22 88 22.60 22.48 26.61 26.94 26.99 30.40 29.98 30.08 36.69 36.60 36.61
102.23 100.98 100.44 98.05 99.26 99.45 100.69 99.30 99.64 100.30 100.05 100.08
100.06
47.21 47.35 46.99
100.29 1cQ.59 99.83
100.49
34.14 34.11 34.41
100.26 100.17 101.05
42.20 41.80 42.22 12.37 12.41 12.11 28.29 28.49 28.62 4.72 4.69 4.85
1cQ.19 99.24 100.24 98.88 99.20 99.80 99.33 100.03 100.49 98.53 97.91 101.25
APPARATUS
Erlenmeyer or iodine flasks, 500-ml. with 24/40 ground-glass stoppers. Ground-glass tube, 24/40, closed a t lower end, into which a platinum wire 6 cm. long (No. 16 B. & S. gage) has been fused. The wire is wrapped around the sharpened portion of a lead pencil to form a helical basket. The lower end of t h e helices is bent over t o prevent the sample from falling out (Figure 1). Gelatin capsules (No. 00000). Filter paper sample carrier 3 em. square with a 5 X 3 mm. fuse. PROCEDURE I
Solid samples of organic matter containing 5 to 10 mg. of sulfur are accurately weighed on a filter paper carrier; liquids are best handled in a gelatin capsule. The capsule may be conveniently supported on a small cork stopper containing a small hole in which the capsule will stand upright. These weighings are preferably done for greater precision on a semimicro or micro analytical balance. In the case of the gelatin capsule, a piece of filter paper, approximately 2 mm. wide and 5 to 6 cm. long, is inserted between the two sections and permitted to project out of the capsule. This eventually acts as a fuse for ignition of the sample.
4Neopentyl-1,2-dithio-4-eyclopen-
tene-3-thiane
4-Neopentyl-l,%dithiocyclopen-
tene3-one
Av. deviation, % Standard deviation, % ’
I
99.83 =t0.72 100.15 zt 0.57
Procedure I1 Thiourea.
42.12
41.88
99.43
Diphenylthiocarbazone
12.51
12.29
98.24
Sodium diethyl dithiocarbamate
28.48
28.28
99.30
4.79
4.90
102.29
Tetrabromophenol sulfonphthalein Av. deviation, % Standard deviation, Yo ~~
*
99.83 1.24 99.59 zt 0.75 ~
VOL. 30, NO. 3, MARCH 195f
ously for a few minutes, so that the peroxide solution will completely absorb the gaseous fumes which have evolved from the reaction. Distilled water, 300 ml., is introduced into the flask and the mixture is shaken for a minute longer. The spiral is removed and washed with a few milliliters of distilled water, and the washings are caught in the flask. The flask is placed on a hot plate and boiled until the volume of solution has been reduced t o 50 ml. It is then cooled under a stream of cold tap water, 2 drops of methyl red are added, and the solution of sulfuric acid is titrated with 0.02N sodium hydroxide solution to a yellow end point. For the liquid samples a blank determination on the gelatin capsule was run, by merely omitting the sample. Small capsules obtained from a local drug store required 1.10 ml. of 0.02N sodium hydroxide. CALCULATION I (Volumetric) M1. of NaOH X N X 16.03 X 100 Weight of sample
= %S
PROCEDURE I1
This procedure is employed for determining organic sulfur in compounds containing nitrogen, halides, phosphorus, or metals. The sample is treated as in Procedure I to the point where it is reduced t o 50 ml. It is then washed into a 250-ml. beaker, 3 ml. of 0.1N hydrochloric acid are added, and, while the sample is still hot, 2 to 3 ml. of 10% barium chloride solution are added dropwise with continuous stirring. The beaker is covered with a watch glass and permitted to stand undisturbed for 2 hours. The precipitate of barium sulfate which has formed is then transferred to a previously tared and dried Gooch crucible. The precipitate is washed six times with 25-ml. portions of dilute hydrochloric acid (1 t o 300) solution, dried in a n
oven a t 110” C. to constant weight, cooled in a desiccator, and weighed on a micro or semimicro analytical balance. CALCULATION I1 (Gravimetric) Weight of BaSOl X 0.1374 X 100 Weight of sample DISCUSSION
-
%S
This makes the method very adaptable t o the requirements of industrial laboratories. Methods for the determination of phosphorus are being investigated and show promise. Work on other elements is also being considered.
OF RESULTS
The procedure as described provides a simple, economical, rapid, safe, and accurate method for determination of sulfur in organic compounds. A number of organic sulfur compounds prepared and purified in the organic department of this laboratory and several commercially available pure compounds were analyzed by Procedures I and 11. The results (Table I) compare favorably with those by the Parr combustion method. The technique as described was found to be perfectly safe and eliminated the hazard of using strong oxidizing agents, such as sodium peroxide, for the Parr method and fuming nitric acid for the Carius method. The procedure is especially convenient for working with compounds of unknown reactivity. Explosions which have occurred using sodium peroxide have been eliminated. On a costwise basis, the equipment used represents a small fraction of the purchase price of combustion bombs and Carius combustion furnaces. These analyses can be run in any laboratory with a minimum cost and time. The method has general applicability and can be used for almost any type of organic matter containing sulfur, including compounds containing as high as 50% sulfur. After combustion of the organic matter in the flask, the sulfur can be determined by any method for elementary determination of sulfur.
LITERATURE CITED
(1) Carius, L., Ann. 116, l(1860). (2) Carius, L., Ber. 3,697 (1870). (3) Hallett, L. T., Knipers, J. IT., IND.Em. CHEY., ANAL. ED. 13, 357 (1940). (4) Horeisrhys, K., Buhler, F., Mikiochemie ver. Mxrochim. Acta 33, 231 (1947). (5) Kuck. J. A.. Griffel. M.. IND.EXG. CHEM.,ANAL. ED: 12,’125 (1940). (6) hlikl, O., Pech. J., Chem. listy 46,
382 (1952). (7) Kiederl, J. B., Xiederl, V., “Micromethods of Quantitative Organic Analysis,” 2nd ed., p. 182, Wiley, New York, 1942. (8) Parr Instrument Co., Moline, Ill., Parr Manual 12, 1950. (9) Pell, E. W., Clark, R. H., Wagner, E. C., IND.ENG. CHEM.,AKAL. ED. 15, 149 (1943). (10) Pregl, F., 4th English ed., p. 101, Blakiston. Philadehhia. 1948. (11) Schoniger, W., Miklcrochim. Acta 1955, 123. (12) Ibid., 1956,869. (13) Scott, T. W., “Standard Methods for Chemical Analysis,” 5th ed., ed. by N. H. Furman, Vol. 11, p. 1643, Van Kostrand, New York, 1929.
(14) Steyermark, A., “Quantitative Organic Microanalysis,” p. 156,
Blakiston, New York, 1951. (15) Steyermark, A., Barr, E. A , , Littman, B., ANAL.CHEM.20,587 (1948). (16) Warshowsky, B., Shook, T. S., Schantz, E. J., Ibid., 26, 1051 (1954).
RECEIVEDfor review June 27, 1957 Accepted November 13, 1957.
Field Sampling and Analysis of Micro Quantities of Sesquimustard in Presence of Mustard ABRAHAM KOBLIN U. S. Army Chemical Warfare laboratories, Army Chemical Center, Md.
An analytical technique has been developed whereby mustard and sesquimustard can b e determined quantitatively in the presence of each other. Both compounds are analyzed by two different techniques and from simultaneous equations derived from the slopes of the colorimeter calibration curves; the quantity of each can b e estimated. The adoption of this technique has reduced the complexity
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ANALYTICAL CHEMISTRY
of field sampling techniques of these compounds and has provided means of obtaining more reliable data, especially when tests are conducted a t lower temperatures.
A
arose to determine microquantities of sesquimustard in the presence of equal or large quantities of mustard. Sesquimustard, bis(2-chloKEED
roethylmercapt0)-ethane, has a melting point of 56” C. and is a white crystalline solid at room temperature. Mustard gas, on the other hand, has a melting point of 14’ C. and is a waterwhite liquid at room temperature when pure. Both of these compounds are strong vesicants. From laboratory and pre-exploratory field studies, it was found that mustard was one of the primary decomposition
