Determination of Traces of Carbon Monoxide in Ethylene HAROLD SIMMONS BOOTH AND MADELINEB. CAMPBELL,Western Reserve University, Cleveland, Ohio HE importance of carbon monoxide when it occurs as an i m p u r i t y in an anesthetic gas cannot be overestimated. Its affinity for the hemoglobin of the blood is variously reported to be from 210 to 300 times that of oxygen (9, 16, Sf,37). Since the carbon monoxide-hemoglobin c o m p o u n d that results is very stable, the oxygen-carrying power of t h e blood is seriously interfered with and tissue respiration impaired. It is obvious that the presence of even small traces of carbon monoxide in an anesthetic gas constitutes a serious danger. Early in the use of ethylene, cases were reported in which carbon monoxide poisoning occurred (35), but ethylene for anesthetic use which is free of carbon monoxide
Yellow oxide of mercury is quant i t a t i v e l y reduced by carbon monoxide a t temperatures rangingfrom 0” to 100” C. (10, $0). No report was found indicating that ethylene reacts with this oxide, though it is well established that ethylene forms complex compounds with some of the mercury salts, notably mercuric cyanide, nitrate, and iodide (17, 40). Possibly the reduction of yellow oxide of mercury could be developed into a satisfactory test f o r c a r b o n m o n o x i d e in the presence of ethylene. Numerous p r o c e d u r e s have been described for d e t e c t i n g the presence of carbon monoxide in air, based on the formation of carbon monoxide hemoglobin. S m a l l a n i m a l s such as mice, canaries, and rabbits have been exposed to the air of mines, tunnels, etc., and by examination of their blood after exposure it has been possible to detect very minute traces of the gas (4, 6, 12). This could not very well be done in the presence of high concentrations of ethylene because of the effect of ethylene itself upon the animals. I n other hemoglobin methods that have been reported, the gas mixtures are brought into direct contact with solutions of blood or of hemoglobin (68,36). The procedure developed by Sayers, Yant, and Jones is very widely used t o detect carbon monoxide in air (34). The air is brought into contact with carbon monoxide-free blood for a period of time long enough to permit the formation of the carbon monoxide hemoglobin, and the blood is then treated with a mixture of solid pyrogallic and tannic acids to form a colored suspension. This is then matched with standards, a blood blank being run a t thr same time. This method will detect 0.005 per cent by volume of carbon monoxide in the air in regions of 0 to 0.05 per cent even by inexperienced observers. A possible objection t o the adaptation of the method to the detection of carbon monoxide in ethylene is the formation of a compound of ethylene and hemoglobin, as has been described by Manchot (25). It will be shown, however, that by calibrating the color standards to known values of carbon monoxide in ethylene, satisfactory results can be obtained. I n order to increase the sensitivity, methods of concentration were considered.
AS SHOWN I N the literature, there is great dificulty in determining traces of carbon monoxide in the‘presence of ethylene. The pyrotannic blood method is shown to be the most j’easible for this purpose, and a recalibration of the “Pyrotannic Detector’’ color standard is given for use with carbon monoxide-ethylene mixtures. A method of concentrating the carbon monoxide by fractional distillation at pressures less than atmospheric is described wherein the sensitivity of the pyrotannic blood method m a y be extended from 10 to 40 times. All of the carbon monoxide is shown to be obtained by this method in samples taken at the beginning of the Jirst two distillations. Oxygenation of the reagent blood eliminates the necessity for running blanks. can now be obtained.
METHODS OF DETERMINING CARBON MONOXIDE In detecting traces of carbon monoxide in ethylene, two obstacles are present that are not met with in determining the carbon monoxide content of other gas mixtures, such as the air of tunnels, garages, etc. These are (1) that very minute amounts of carbon monoxide must be detected, and (2) that in properties and behavior carbon monoxide and ethylene resemble each other very closely. Though there are numerous satisfactory methods for the determination of the carbon monoxide content of air, some of which detect as little as 0.01 per cent by volume, they are not directly applicable to the problem of detecting smaller amounts of gas, especially in the presence of large amounts of the unsaturated hydrocarbon ethylene. The method of drawing air through a solution of iodine pentoxide and measuring the carbon monoxide content by the amount of iodine liberated cannot be used in the presence of ethylene, since unsaturated hydrocarbons give the same reaction (11, 14, 15, 18, 13,94, 36). Absorption of the carbon monoxide in solutions (either acid or ammoniacal) of cuprous chloride is unsatisfactory, since these also absorb ethylene, and some preparations absorb as much of one gas as of the other (7, 8,41). Tests depending upon the reduction of palladium chloride with the deposition of black metallic palladium are likewise not applicable in the presence of unsaturated hydrocarbons (3, 96). Nickel forms nickel carbonyl, Ni(C0)4, with carbon monoxide a t ordinary temperatures and, except for possible adsorption, there appears to be no reaction between nickel and ethylene. Nickel carbonyl is an unstable liquid, easily decomposed to give carbon monoxide. This reaction might be adapted to the detection of carbon monoxide in ethylene (10). 1 Holder of one of The Ohio Chemical and Manufacturing Company Graduate Fellowships for pure science research in anesthetic gases, 1927-29.
METHOD OF CONCENTRATING CARBON MONOXIDE The removal of the ethylene before applying one of these tests, by absorption in fuming sulfuric acid or bromine water, might be applied to gas mixtures containing appreciable amounts of carbon monoxide, but this is not possible for amounts as low as one part or less in ten thousand. Even if the carbon monoxide were not lost in the manipulation, it would be lost by solution, since it is soluble to the extent of 2.33 cc. in 100 cc. of 95.6 per cent sulfuric acid, and is
131
132
AXALYTICAL EDITION
more soluble as the concentration of the acid increases (21). Furthermore, it reacts with bromine, especially in the light, to form carbonyl bromide. All non-aqueous liquids on which data were found dissolve more ethylene than carbon monoxide. Separation of the carbon monoxide by simple solution is therefore not feasible (2, 22, 27). Both gases are adsorbed by numerous solid substances, including activated charcoal, dry hemoglobin, and certain preparations of nickel, copper, cobalt, iron, palladium, and platinum (13, $3, 38, 39). Carbon monoxide is much more extensively adsorbed than ethylene by charcoal and platinum black, and perhaps a concentration of this gas could be accomplished by this procedure.
FIGURE 1. FRACTIONATING APPARATUS
The specific gravity, referred to air, of ethylene is 0.978, and of carbon monoxide, 0.967 (19). This excludes the possibility of separation or concentration of one component from mixtures of these two gases by diffusion. The wide difference between the boiling points of the two gases suggests a t once the separation by fractional distillation a t low temperatures, Carbon monoxide boils a t -192’ C. and ethylene a t -103.8” C. (20). This method has been made use of bv Burrell and Robertson and
Vol. 4, No. 1
fractionations here described were conducted a t atmospheric pressures. A small steel gas cylinder (size “D”) (1)was evacuated and filled to atmospheric pressure with carbon monoxide prepared from oxalic and sulfuric acids, and then with ethylene until the concentration of carbon monoxide was 0.01 per cent. The fractionation apparatus of the intermittent type was constructed, as shown in Figure 1, entirely of glass, the parts being fused together with a hand torch. The only rubber connections were a t T and C, where the cylinder and the sample bottle were connected to the apparatus. These connectians were as short as possible, and were made of heavy pressure tubing; they held a vacuum satisfactorily. J and G were the bulbs in which the gas was condensed by bringing liquid air in a Dewar flask up around them. K and ?I were mercury safety manometers to indicate the pressure in J and G, respectively. A was a sample bottle of 300 cc. capacity, and E a safety manometer to indicate the pressure of the sample. L was a manometer for testing the efficiency of the pump. The entire apparatus was evacuated by a rotary oil vacuum pump connected a t P. The cylinder was then put in place and heated by surrounding it with water well above the critical temperature of ethylene. All stopcocks were closed, separating the fractionating bulbs and the sample bottle from one another. Liquid air was brought up around J , the cylinder valve, valve V , and stopcock 8 were opened, and ethylene condensed as a solid in the bulb. Since the gas in the cylinder was entirely in the gaseous phase, this was a representative sample of the contents of the cylinder. When 25 cc. of liquid ethylene had been condensed, the valves and stopcock were closed, and the ethylene in the bulb allowed to liquefy. When the liquid began to boil, the stopcocks N , D, and B were opened and a sample of gas collected in the sample bottle, When the pressure had reached atmospheric, as shown by the manometers K and E , stopcocks B and D were closed, and liquid air brought up around bulb J momentarily to prevent the pressure from increasing above atmospheric. The sample bottle was disconnected and a second one put
January 15, 1932
133
TNDUSTRIAL AND ENGINEERING CHEMISTRY
the distillation the process was interrupted to collect a third sample. L4fourth sample n7as taken a t the end of the distillation. All of the ethylene except that taken in samples 1 , 2 , 3, and 4,was now in bulb G. It was allowed to liquefy and, when boiling began, two consecutive samples, 5 and 6, were taken. The gas was then distilled back into bulb J by surrounding it with liquid air. Midway of the distillation, sample 7 was taken. A third distillation was then made, condensing the ethylene again in bulb G. Sample 8 was taken a t the start of this distillation, sample 9 midway, and sample 10 at the end. The remaining ethylene was discarded through a gas meter. The gas samples mere then analyzed by the pyrotannic blood method, the procedure being as follows: A 1 t o 20 dilution in water was made of blood from (animal) subjects that had not been exposed t o carbon monoxide. Two cubic centimeters of this were run into the sample bottle containing the gas, which was re-corked immediately. The bottle was held in a horizontal position and rotated for 15 minutes, using a rotating machine. The blood was then poured into a small glass tuhe, 8 by 40 mm., and an equal amount of the diluted blood was placed in a similar tube to serve as a blood blank. Then 0.04 gram of 1 t o 1 solid mixture of pyrogallic and tannic acids was added to each tube to develop the color and to form the colored suspensions. All of the procedure up to this point was conducted in a dimly lighted place. At the end of 15 minutes the tubes were compared with colo~standards by holding them against a dull black background, using reflected light. Sunlight or artificial light is not satisfflctory. The tests should not be run where there is any likelihood of carbon monoxide being present in the atmosphere. The color standards used were the “Pyrotannic Detector” set put out by the Mines Safety Appliance Co. of Pittsburgh, which had been recalibrated t o ethylene-carbon monoxide mixtures. For this purpose accurate synthetic mixtures with 0.003, 0.005, 0.02, 0.05, 0.1, and 0.2 per cent carbon monoxide were made by first making accurate 5.0 per cent mixtures and diluting with pure ethylene in accurate mercury gas burets to these concentrations.
Table I gives briefly the recalibration, the readings being the averages of three sets of determinations, each observation made by four observers. TABLEI. RECALIRRATION OF COLORSTANDARDS COLOR-SCALI
CARBON MONOXtDE IN ETHYLENE
1.008 cc., or 0.010 per cent by volume. This is close to the lower limit of sensitivity of the test if determined directly, yet, as shown by the results given above, concentration by two fractionations made it quantitatively determinable. This fractional distillation was repeated a number of times with the same results. To demonstrate further the value of the preliminary concentration of the carbon monoxide, and to confirm the results given above, a few results obtained by using specimens of crude ethylene are given in Table I11 showing how all the carbon monoxide is concentrated in the first fractions. OF S4MPLES OF GASFROM FRACTIONATION TABLE 11. ANALYSES
cc. 1. First, distillation taken a t beginning
6. Second, taken at beginning of 2nd distillation 7. Taken a t mid-point of 2nd distillaGion 8 . Taken a t beginning of 3rd distillation 9. Taken a t mid-point of 3rd distillation 10. Taken a t end of 3rd distjll?tion Blood blank (correction insignificant)
80 75
0.3 0.2 0.1
70 65 50
40 30 20 12
0.05 0.02 0.005 0.003 0.001 0.0005 Blood blank
0 0 0
This shows the color scale not to be sensitive below a reading of 12, which represents 0.003 per cent by volume of carbon monoxide in ethylene. The curve for these values is given in Figure 2.
RESULTS The results obtained by the analyses of the samples of gas from the fractionation of the carbon monoxide-ethylene mixture are shown in Table 11. The results in Table I1 show that all of the carbon monoxide present in the ethylene was obtained in the samples taken a t the beginning of the first two distillations. Calculating the ethylene content of the three samples, 1, 2, and 5, on the basis of 300 cc. capacity for the sample bottles, the carbon monoxide content of the 10,100-cc. specimen amounted to
70
0 . 2 3 X 300 = 0.69
45 2 2
0.074 X 300 = 0.222 None None
35
0.032 X 300 = 0.096
5
Xone None None None None
2 2 2
2 2
Total
1.008
TABLE 111. RESULTSWITH CRUDEETHYLENE CRVDE
ETHYLENE SPECIMEN
CARBOX COLOR-SCALE XOXOXIDE EQUIY. I N READING I N S I M P L E ORIQIN4L
%
Sample 2, at beginning
%
1
BPECIMEN NO.
10
5
Blood blank SPECIMEN
NO.
a
Sample 1, a t beginning
30
Sample 2, a t beginning
10
2nd distillation Sample 1, a t beginning Blood blank
{
Less than 10 10
0.020 oorr.=0.00044 t o 0,018 None None None
SPECIMEN NO. 8
lst dis-
0.5 0.4
1st
of
2. Second, taken a t beginning of 1st distillation 3. Taken a t mid-point of 1 s t distillation 4. Taken a t end of 1st distillation 5. First, taken a t beginning of 2nd distillation
READINQ
%
COLOR-SCALE CARBON MONOXIDE IN SAMPLE READING
SAAf PLE
Sample 1, a t beginning
1 Sample Sample 2, a t beginning 1 a t beginning
i
2nd distillation Sample 2: a t beginning Blood blank
38
16 10 10 15
0.042 corr.=0.00088 t o 0.038 None None None None
The quantitative application may be shown by calculating the carbon monoxide content of specimen No. 1 from the data given in this table. All of the carbon monoxide was obtained in the first sample of the first distillation, and amounted to 0.011 volume per cent, but the blood blank color-scale reading of 5 was equivalent to 0.001 per cent, leaving a real value of 0.010 per cent or 0.030 cc. of carbon monoxide in the 300-cc. sample. This is equal to 0.00024 per cent of the carbon monoxide in the 12,600CC. of gas taken from the cylinder and is considerably below the sensitivity limit of the direct test. Without the preliminary fractionation it could not have been determined. Charles H. Wardell, chief chemist of the Ohio Chemical and Manufacturing Company, in using this method for 3 years in controlling the purity of anesthetic ethylene, has found that, by oxygenating the blood before use by bubbling through it pure oxygen to a constant bright color, the blood blank becomes zero, thus simplifying the calculations greatly. It has been found also that oxygenated blood will keep in excellent condition in an electric refrigerator for over a week
ANALYTTCAL EDITION
134
if in a tightly stoppered bottle, whereas the untreated blood rapidly deteriorates. To calculate the extent to which the sensitivity of the test is increased by this means, it is merely necessary to determine the ratio between the amount of gas taken from the cylinder and the amount taken as samples for the pyrotannic blood determination. If three samples are allowed, which, as has been shown, is a safe margin for obtaining all of the carbon monoxide, the ratio is 12,600 to 900 (3 X 300), or 1 to 14. As a matter of fact, however, all of the carbon monoxide is obtained in the first two samples taken, so that the ratio is really 1 to 20. Concentration by fractionation readily increases the sensitivity of the modified oxy-hemoglobin test 20 times. Obviously, by increasing the amount of the sample the sensitivity can be correspondingly increased. ACKNOWLEDGMENT We gratefully acknowledge the helpful suggestions and great assistance of Messrs. Wardell and Glekler of the research laboratory of the Ohio Chemical and Manufacturing Company in making this study. LITERATURE CITED (1) Booth, H. S., J . Chem. Education, 7, 1249 (1930). (2) Brooks, B. T., “The Non-Benzenoid Hydrocarbons,” p. 160, Chemical Catalog, 1922. (3) Bnmck, O., Z. angm. Chem., 25, 2479 (1912). (4) Burrell, G. A,, Bur. Mines, Tech. Paper 11 (1912). (5) Burrell, G. A., and Robertson, I. W., J. IND. ENQ.CHEX., 7, 210 (1915). (6) Burrell, G. A,, and Siebert, F. M., Ibid., 6, 241 (1914). (7) Czako, E., J. Gusbet., 57, 169 (1914). (8) De la Condamine, M., Compt. rend., 179, 691 (1924). (9) Douglass, C. G., Haldane, J. S., and Haldane, J. B. S., J. Physiol., 44, 275 (1912).
Vol. 4,No. 1
(10) Fay, I. W., and Seeker, A. F., J.A m . Chem. Soc., 25,646 (1903). (11) Graham, J. I., J . SOC.Chem. Ind., 38, 10-4T (1919). (12) Grehant, N., Compt. rend. SOC. b i d , 66, 69 (1909). (13) Harbeck, E., and Lunge, G., Z. anorg. Chem., 16, 50 (1898). (14) Harger, J., J . Chem. Met. Mining SOC.S. Africa, 15, 59 (1914). (15) Harger, J., Trans. Inst. Mining Eng., 1914, 533. (16) Henderson, Y., J . A m . Med. Assocn., 67, 580 (1916). (17) Hoffmann, X. A., and Sand, J., Be?., 33, 1340 (1900). (18) Hoover, C. R., J. IND.ENG.CHEW,13, 770 (1921). (19) International Critical Tables, Vol. 111,p. 3, McGraw-Hill, 1926. (20) Ibid., Vol. I , p. 179 (1926). (21) Ibid., Vol. 111, p. 265 (1928). (22) Just, G., 2. phys. Chem., 37, 342 (1901). (23) Katz, S. H., and Bloomfield, J. J., J. IND.ENG.CHEM.,14, 304 (1922). (24) Levy, L. A., J. SOC.Chem. Znd., 30, 1437 (1911). (25) Manchot, W., Liebig’s Ann. Chem., 370, 241 (1909). (26) Manchot, W., and Brand, W., Ibid., 370, 286 (1909). (27) McDaniel, A. S., J. Phvs. Chem., 15, 587 (1911). (28) McLoud, M. C., Coal Age, 23, 1007 (1923). (29) Mond, L., Langer C., and Quincke, F., J. Chem. SOC.,57, 749 (1890). (30) Mpser, L., and Schmid, O., Z. anal. Chem., 53, 217 (1914). (31) Nicloux, M., Compt. rend. SOC. biol., 89, 1331 (1923). (32) Nicloux, M., Bull. SOC. chim., 33, 818 (1923). (33) Pollard, F. H., J. Phys. Chem., 27, 356 (1923). (34) Sayers, R. R., Yant, 1%’. P., and Jones, G. W., Bur. iMines, Rept. Investigations 2486 (1923). (35) Sherman, W. O., Swindler, C. M., and McEllroy, W. S., J. Am. Med. Assocn., 86, 1765 (1926). (36) Sinnott, F. S., and Cramer, J., Analyst, 39, 163 (1914). (37) Sollmann, T., “A Manual of Pharmacology,” p. 766, Saundera, 1927. (38) Taylor, H. S., J. IND.ENG.CHEM.,13, 75 (1921). (39) Taylor, H. S., and Burns, R. M., J. A m . Chem. Soc., 43, 1273 (1921). (40) Treadwell, W. D., and Tauber, F. A., Helv. Chim. Acta., 2, 601 (1919). (41) White, A. H., “Gas and Fuel Analysis,” p. 36, MoGraw-Hill, 1920.
‘
RECEIVED September 22, 1931.
Germanic Sulfide Quantitative Conversion of Sulfide t o Dioxide by Hydrolysis JOHN HUGHES MULLER AND ABNEREISNER, University of Pennsylvania, Philadelphia, Pa.
G
ERMANIC sulfide is usually converted to dioxide by repeated t r e a t m e n with nitric acid followed by evaporation and ignition to expel sulfuric acidfrom the r e s i d u a l oxide. It is known that this reaction is quite violent and that to cut down if the acid is the violence of the o x i d a t i o n , much free sulfur separates which is difficult to remove by subsequent treatment with excess of the oxidant. Small amounts of
GERMANIC SULFIDE can be conveniently transposed to dioxide by simple hydrolysis, the decomposition efected by injecting a current Of into the water suspension Of the su@de* Hydrolytic decomposition of the sulfide in larae masses is of special advantage because all processe8 involving oxidation of the su&de ape attended with violent reaction and accompanying errors* Germanium can be quantitatively determined by hydrolyzing the sulJide directly to oxide, when it is weighed, Elimination of the sulfur a s hydrogen sulfide avoids sources of error common to methods involving oxidation of the su@de.
“Ifide Ordinarily with in the quantitative determination of gemanium may be converted t o oxide in this way, but even here results are likely to be low unless extraordinary care is taken to prevent mechanical loss. The first decided improvement in the determination of oxide from the sulfide was described by Johnson and Dennis ( I ) . These investigators dissolve the precipitated sulfide in ammonium hydroxide, oxidize with hydrogen peroxide, evaporate, and ignite to oxide.
The present paper describes a new method of c o n v e r t i n g large or small a m o u n t s of germanic sulfide to germanic oxide by simple hydrolysis in which all of the sulfur is removed as hydrogen sulfide. The authors claim t h a t t h e h y d r o l y t i c d e c o m p o s i t i o n of the sulfide may be advantageously used both for an accurate determination of germanium and for the rapid conversion of large masses of the bulky sulfide to oxide in the preparation of pure germanium compounds~
EXPERIMENTAL PROCEDURE A quantity of germanic sulfide was precipitated from a 6 N hydrochloric acid solution of the dioxide. (Arsenic-free
material was used throughout.) The precipitation was carried out with hydrogen sulfide under pressure in a closed system to exclude air. The bulky white sulfide was rapidly filtered on Biichner funnels and mashed with dilute hydro-
