June 15, 1942
ANALYTICAL EDITION
TABLE 111. RATEOF DISAPPEARANCE OF ETHYL ALCOHOLFROM BLOODO F INTOXICATED P E R S O N Time after Taking First .%lcohol in B:ood Sample Blood Hours . V ~ . / 1 0 0ml 0 304, 310
3 6.5 9 12
214. 256 164, 168 9.5, 97 32, 38
Condition of Subject Moderate t o severe intoxication. speaks with difficulty UncooDerative. fiehtine restraints Quiet i n d sleepyFairly rational Rational
hol to dogs. It was thought of interest to make a series of similar measurements with a human subject, t o illustrate further the use of the present method over a wide range of alcohol concentration. Table I11 gives the results obtained for a 12-hour period with a patient mho is classified in the “moderate to severe” range of intoxication in Table 11. If the alcohol values are plotted against the corresponding times, the points fall along a straight line.
Summary The Conway microdiffusion unit has been adapted to the determination of ethyl alcohol in blood and urine. The alcohol diffuses from the sample in the outer chamber of the unit into the central chamber, where it is oxidized b y a solution of potassium dichromate. The excess dichromate is determined iodometrically
525
Some illustrative alcohol concentrations in blood and urine during intcxication are re,ported. A number of industrially important organic compounds whose vapors can cause drunkenness resembling ethyl alcohol int’oxication were tested for possible interference with the method.
Acknowledgment The writer appreciates the advice and ass.oLance given bin1 by C. G. Johnston and I. B. Taylor, relative to the clinical phase of this study. He wishes also to thank C. P. McCord and G. C. Harrold, of the Industrial Hygiene Department, Chrysler Corporation, Detroit, for supplying some of the organic compounds tested, and for helpful information.
Literature Cited (1) Cavett, J. W., J . Lah. Clin. M e d . , 23, 543-6 (1938). (2) Conway, E. J., “Microdiffusion Analysis and Volumetric Error”, London, Crosby Lockwood and Son, 1939; Biochem. J . , 27, 419-34 (1933). (3) Gibson, J. G., and Blotner, H., J . Biol. Chem., 126, 551-9 (1938). (4) Goodman, L.. and Gilman, A., “Pharmacological Basis of Therapeutics”, New York, Macmillan Co., 1941. (5) Jetter, W.W., Quart. J . Alcohol, 2, 512-43 (1941). (6) Levine, H., and Bodansky, M., Am. J . Clin. Path., Tech. Section 3, 159-73 (1939). (7) Nemman, H. W., Lehman, A . J., and Cutting, W.C., J . PharmaC O ~ . .61, 58-61 (1937). (8) Widmark, E. M.P., Biochem. Z . , 131, 473-84 (1922). (9) Winnick, T., J . B i d . Chem., 141, 115-20 (1941): 142, 461-66 (1942). AIDED by a grant from the 3IcGregor Fund.
Semimicrodetermination of Carbon Using the Van Slyke-Folch Oxidation Mixture R . \I. MCCHEADY AND W. Z. H A S S I D , D i v i s i o n o f P l a n t N u t r i t i o n , b-niversity o f California, Berkeley, Calif.
V AS
SLYKE and Folch (4) pointed out that all the wet carbon combustion methods hitherto employed were unsatisfactory because the oxidizing mixtures used did not give quantitative results with the more difficultly combustible compounds. For this reason these methods did not find a place in the organic laboratory. X e t combustion methods were tried in this laboratory employing either a n iodic acid (3) or chromic acid (2) oxidizing mixture, but the results were unsatisfactory. While theoretical results could be obtained with many organic compounds, certain substances such as sugar acetates and some organic acids invariably gave low results. The Van SlykeFolch (4) manometric method, in which a n oxidizing mixture, consisting of fuming sulfuric, phosphoric, chromic, and iodic acids was used, gave excellent results with all the compounds tried. Equally satisfactory results were obtained using the Van Slyke-Folch oxidizing mixture, and a simple apparatus, whereby the carbon dioxide evolved was absorbed in alkali and weighed. Inasmuch as the Van Slyke manometric apparatus is not available in many laboratories, the following procedure, requiring simple manipulation and inexpensive equipment, is described.
Reagents Van Slyke-Folch combustion mixture: 25 grams of chromium trioxide, 5 grams of potassium iodate, 167 ml. of sirupy phosphoric acid (specific gravity 1.7); and 333 ml. of fuming sulfuric acid (20 per cent free sulfur trioxide) are placed in a 1-liter Pyrex Erlerimever flask provided with a ground-glass stopper. The
open flask containing the mixture is heated over a wire gauze with a flame, until the temperature reaches 140” to 150” c‘. During heating, the flask is occasionally rotated to assist in the solution of the chromic anhydride. When a temperature of 150” c‘. has been reached, the flame is removed, the flask covered with an inverted beaker, and the mixture allowed to cool to room teniperature. The glass stopper is then inserted, and an inverted beaker is kept over the stopper to prevent the solution from being contaminated with dust. Potassium iodate, reagent grade, pulverized. Dehydrated phosphoric acid, prepared from 85 per cent acid by boiling.
Apparatus The apparatus is shown in Figure 1. Tubes A A are filled with soda lime and serve to obtain carbon dioxide-free air. The reaction flask, B , has a 15-1111. capacity and is connected to a reflux condenser, C, with a 14/35 standard taper glass joint. The construction of an Allihn condenser is modified (Figure 2) to contain a cold-water column inserted into its center. This modification greatly increases the efficiency of the condenser. A 5-ml. capacity cup, D, with a stopcock, b, forming part of the condenser, serves to introduce the oxidizing mixture into the reaction flask. Stopcock b is greased with viscous dehydrated phosphoric acid. The rest of the stopcocks are greased with ordinary stopcock grease. E is a bubble counter containing 0.5 ml. of concentrated sulfuric acid. A small glass-wool plug is inserted into each of its arms to trap any sulfuric acid which might splash over to tube F or condenser C. F is filled with granular zinc (30-mesh) to trap any volatile acids which form in the determination. The moisture-absorption tube, G, is filled with Anhydrone (rnagnesium perchlorate) leaving 1-em. space at each end for a glssswool plug. Previous to use in the apparatus, a slow stream of
526
INDUSTRIAL AND ENGINEERING CHEMISTRY
carbon dioxide is passed through G for 1 hour, then allowed to stand for 2 hours in contact with the gas, and finally dry carbon dioxide-free air is drawn through to displace the unabsorbed carbon dioxide. The carbon dioxide absorption tube, H , is filled with Ascarite (asbestos impregnated with sodium hydroxide, o b t a i n e d f r o m A r t h u r H. Thomas Company) and a 1-cm. layer of Anhydrone at each end of the U-tube. Tube I c o n t a i n s g r a n u l a r calcium chloride and is used to prevent backward diffusion of moisture and air. The parts of the apparatus are joined with heavywalled rubber tubing.
Vol. 14, No. 6
I 1
- 20
MM.
00
1
G
A
4 d
e
C
Determination The sample (5 to 30 mg., depending upon t h e c a r b o n content) is,wejghed on a s e m i m i c r o balance to an accuracy of 0.02 mg. A less sensitive analytical balance may be used, if the method of weighing recommended by BenedettiPichler is used (1). The sample is then placed in the dry combustion flask. If the sample is aqueous and is nonvolatile, an aliquot, preferably not more than 2 ml., is introduced with a pipet, acidified with a drop of c. P. hydrochloric acid, and evaporated to dryness. Three hundred milligrams of potassium iodate are added, and the flask is joined to the condenser, the ground joint being greased with dehydrated phosphoric acid, and held in place by a coiled spring. lT7ith stopcocks a, b, and d closed, the apparatus is evacuated by applying suction through stopcock c (about 60 mm. of mercury pressure is sufficient) until bubbles cease to appear in the bubble counter. Stopcock c is closed and disconnected from suction. The apparatus is maintained under partial vacuum during the combustion. Four milliliters of the Van Slyke-Folch mixture are poured into cup D,and introduced into the reaction flask by opening stopcock b, care being taken to prevent air from entering the apparatus. The combustion flask is heated with a microburner at such a rate that its contents will come to a boil within about 2 minutes, and the boiling is then continued for 1 minute. When the combustion is completed, stopcock a is slightly opened (so that no more than one bubble per second passes through the bubble counter) and carbon dioxide-free air is let into the apparatus until normal pressure is established. Stopcocks d and e
TABLE I.
DETERMlN.4TION OF
MR.
Con MQ.
22.82 11.22, 15.30 10.65 24.00 6.48 7.87 14.40 27.34 12.90 13.30 11.18
33.40 16.50 29.47 20.50 44.20 11.85 21.61 49.58 49.76 23.48 33.40 28.20
Sample Substance Glucose 2,3,4,6-Tetramethy1-+4-methylglucoside Starch acetate Palmitic acid Phenylhydrazine hydroch1,oride Benzoic acid
CARBON
FIGERE 1. DIAGRAM OF APPARATUS
are then opened and the carbon dioxide is swept into the absorption tube, H , by connecting the upper part of the calcium chloride tube to suction, and sucking carbon dioxide-free air at the rate of one bubble per second for 15 minutes. Stopcocks d and e are then closed, and the absorption tube is disconnected, carefully wiped with a clean towel, and weighed. The amount of carbon in the samde is obtained bv multiplying the weight'of carbon dioxide by a factor of '0.2727. The results of carbon analysis of six compounds are given in Table I.
Summary A simple apparatus for the semimicrodetermination of carbon in organic com-
FIGURE 2
Carbon Found Calculated
%
%
39.91 40.11 52.53 52.49 50.22 49.87 74.88 74.95 49.63 49.65 68.51 68.78
40.00 52.78
Acknowledgment The authors wish to thank T. C. Broyer for his criticism and suggestions.
Literature Cited
d50.00
74.94 49.82 68.85
pounds, using the Van Slyke-Folch oxidation mixture, is described. This wet oxidation method gave theoretical yields with all the organic substances tried, and the accuracy of the procedure is equal to that of dry combustions. In routine work single determinations require about 30 minutes.
(1) Benedetti-Pichler, A A.,
TND. ENG.CHEM.,ANAL.ED., 11, 226
(1939).
(2) Berl, E., and Koerber. W'., Ibid., 12, 245 (1940). (3) Christensen, B. E . , and Facer, J. F., J . Am. Chem. SOC.,61, 3001 (1939). (4) Van Slyke, D. D., and Folch.
J.,J. Bid Chem., 136, 509 (19401.
