1572
A N A L Y T I C A L CHEMISTRY
(19) Hahn, F. L., and Klockmann, R., 2. p h y s i k . Chem., 146-4, 373 (1930). (20) Hanes, C. S., and Isherwood, E. .L.,Snfrire. 164, 1107 (1949). (21) Hoyer, H., Kolloid-Z., 116, 121 (1950). (22) James, A. T.. and Martin. .I.J. P.. Anulyd, 77, 915 (1952). (23) Kiselev, A. V.,Colloid J . (C.S.S.R.),2 , 17 (1936). (24) Kiselev, 9.V., T’orms, I. A.. Iiiseleva, V. V,, Kornoukova, V. N., and dhtokish, E. A , , J . Phya. Chenr. (C.S.S.R.),19, 83 ( 1945). (25) Kistler, 9. S..Fischer, E. A , , and Freeman, I. I t , , J . Ani. Chem. SOC.,65, 1909 (1943). (26) Kowkabany, G. S . , and Carsidy, H. G.. A I x a ~ CHEM., . 24, 643 (1952). (27) LeRosen, A., J . Ani. Ckeni. Soc., 64, 1905 (1942). (28) Ihid., 6 9 , 8 7 (1947). (29) LeHosen. A. L., Carlton, J. K.. and llosoley, P. B., .4~.41.. CHEY.,25,666 (1953). (30) LeRosen, A. L., Monaghaii I-’. H., Rivet, C. -I.,and Smith, E. D., Ibid., 23, 730 (1951). (31) LeRosen, A. L., llonaghan, P. H.. Rivet. C. .\., Smith, E. D., and Suter, H. -1.. I b i d . , 22, 809 (1950). (32) XIcGavack, J., Jr., and Patrick, W. A. J . Bm. Chent. Soc., 42,946 (1920). (33) Nalmberg, E. W.,Trueblood, K. F.,and Waugh, T. D., .LNAL. CHEM..25,901 (1953). (34) Martin, A. J. P., A m . Reu. Riochem., 19, 517 (1950). (36) Martin, A. J. P.. and Sgnge, R. L. AI., Biochem. J . (London), 35, 1358 (1941). (36) Marvel, C. S.,and Rands, R. D., J r . , J . Am. Cheni. Soc.. 72, 2642 (1950).
(37) (38) (39) (40) (41) (42)
(43) (44) (45) (46) (47) (48) (49) (50) (51) (52) (53) (54) (55) (56) (57)
Xoore, S.,and Stein, W. H., J . Bid. Chem., 192, 663 (1951). Mukherjee, J . N., and Chatterjee, B., :Vatwe, 155, 85 (1945). Patrick, W. h.,and Long, J. S., J . Phys. Chem., 29, 336 (1925). Plank, C. J., J . Colloid Sci.,2 , 413 (1947). Plank, C. J., and Drake, L. C., Ibid.,2 , 399 (1947). Rainsay, L. L., and Patterson, W.I., J . Assoc. Ofic.Agr. Chemisis, 28, 644 (1945). Schroeder, W.A., J . Ani. Chem. Soc., 73, 1122 (1951). Shapiro, I.. and Kolthoff, I. 31.. Ibid., 72, 776 (1950). Shapiro, I., and Weiss, H. G.. .I. Phys. Chwn., 57, 219 (1953). Shull, C. G., Elkin, P. B.. and Hoess, L. C., J . Am. Chem. Soc., 70, 1410 (1948). Sporer, .I.,unpublished data. Stewart, A , Discussions F u m d a y SOC.,KO.7, (1949), 13.5. Strain, H. H.. J . Am. Chem. Soc., 70, 588 (1948). Tiselius, A , Discussions Furudu.y Soc., No. 7, (1949), 7. Trappe, W., Biochem. Z . , 306, 316 (1940). Trueblood, Ia i s of certain mixtures of chloral hydrate and dichloro- or chloroacetaldehyde. Mixtures of dichloro- and chlornacetaldehy-de cannot be analyzed by direct polarographic methods, for the two compounds give coincident wales in the usual buffer systems. The precision for determiuation of the inditidual chloroacetaldehyde alone or in the presence of others as specified is about 3Yo.
MA“
methods have been reported for the quantitative determination of chloral hydrate. Those most frequently used are based upon its reaction with sodium hydroxide to form chloroform and sodium formate, followed by dctermination of the sinount of: (A) alkali consumed (E-6, 8-i1, 15, 14, 16-18, 25, 24, 27, 30, 32, 5.5, J6> 38, 3 0 ) ; (B) sodium formate formed (16, 38); or (C) chloroform produced (30, 58). Method A has several drawbacks-e.g., esperiniental condit.ions such as time, temperature, and stirring must be carefully standardized because the chloroform produced usually reacts to some extent with the excess alkali; the volatility of the chloroform may affect the extent of such reaction; and ot.her substances which independently react with alkali must be absent. Method B is based upon the reducing power of formic acid; therefore, other
reducing agents cannot be present,. Method C is generally inferior to the other procedures, owing to the volat.ility of chloroform and to its possible reaction wit,h excess alkali. Chloral hydrat,e can be oxidized to trichloroacetic :wit1 with iodine (18, 28, 31, 38), bromine (SI), permanganate ( 3 2 ) , or persulfate ( 2 8 ) ; the excess st,andard oxidant is then determined by back-titrat,ion. Other reducing agents must be absent. An obvious procedure is based on the determination of t,otal chlorine as chloride ion. The conversion of ehloral hydrate to chloride ion may be accomplished by coiiiplete hydrolysis with alcoholic alkali (6, 20, S 7 , 3 9 ) or by reduction with zinc in sulfuric acid solution ( 2 2 ) . The chloride is then determined by conventional methods ( 2 2 , 26, 35). This procedure has the distinct disadvant,age that no other halogen compounds ran be present. Other methods for t,he determinat,ion of chloral hydrat,e use color reactions (1, 12, 15, g l ) , specific gravity (S4), and surface tension (8). Several of the methods described could also be used successfully for the determination of either dichloro- or chloroacetaldehyde if it vere the only chloroacetaldehyde present. Dichlor- and chloroacet,aldehyde can also be assayed by an aldehyde determination. These methods described cannot be uscd directly for the analysis oi mixtures of the chloroacetaldehydes. In view of the successful polarographic determination of acetaldehyde and other aldeha-des, an investigation of the feasibility of the polarographic technique n-as desirable for the analysis of mixtures of the chloroacetaldehydes as well as for the rapid determination of tthe individual aldehydes. EXPERLWENTAL
Stock aldehyde solutions (about 10 d ) were repared from U.S.P. chloral hydrate (Merck & Co., Ino., 9 9 . 5 8 pure), a re-
V O L U M E 26, NO. 10, O C T O B E R 1 9 5 4 distilled research sample of dichloroacetaldehyde ( Westvaco Chemical Division, Food Machinery and Chemical Corp.), and a research sample of chloroacetaldehyde (40.0% solution by weight, Dow Chemical Co., composition checked by specific gravity measurement). Nitrogen used for deoxygenating was purified by successive passage through concentrated sulfuric acid, alkaline pyrogallol, distilled water, and a portion of the test solution. The composition of the buffers used were 1.OM ammonium chloride with added ammonia (pH 8.4), and O.082M sodium tetraborate decahydrate with 0.820X potassium chloride (pH 9.2). A Sargent Model XI1 polarograph was used in conjunction with an external potentiometer and a thermostated H-cell (19) employing a saturated calomel reference electrode. A Beckman Model G pH meter was used for pH measurement. All measuring apparatus were calibrated. The dropping mercury electrode prepared from Corning marine barometer tubing had a m Z W 6 value of 1.194 (80-cm. mercury head, 25" C.) a t the potential used for calculating the current of chloral hydrate and a value of 1.213 for dichloro- and chloroacetaldehyde. BASIS FOR THE PROCEDURE
Xeiman (g6)first reported chloral hydrate to be polarographically reducible; Federlin (7) discussed the polarographic behavior of the chloroacetaldehydes. The results obtained in a more recent and more detailed polarographic study of the chloroacetaldehydes (6) were used as the basis for the development of the described analytical methods. The present study has shown that the following analytical applications are feasible: determination of any individual chloroacetaldehyde in the absence of the other two; determination of chloral hydrate in the presence of either or both dichloro- and chloroacetaldehyde; and analysis of certain mixtures of chloral hydrate and either dichloro- or chloroacetaldehyde. The direct polarographic analysis of mixtures of dichloro- and chloroacetaldehyde cannot be performed because the two compounds give coincident. waves in all of the usual buffer systems (6). The determination of the individual chloroacetaldehydes can be accomplished in several buffers; the best results are obtained in ammonia or borate. Although the highest currents are obtained in ammonia buffer a t about pH 9.1, ammonia buffer a t pH 8.4 was selected for analytical work because the waves of mixtures of the compounds are more separated a t this pH; Eli2 values in this medium are - 1.06 and - 1.66 volts for chloroacetaldehyde, - 1.03 and - 1.67 volts for dichloroacetaldehyde, and -1.35 and -1.66 volts for chloral hydrate. The more negative wave in each case is the result of the reduction of acetaldehyde ( 6 ) . Borate buffer (pH 9.2) is satisfactory for t'he determination of chloral hydrate and chloroacetaldehyde, but not for dichloroacetaldehyde which gives a very small wavc; Eli2 values are - 1.07 and - 1.78 volts for chloroacet,aldehyde, - 1.03 volts (first wave; the second wave is poorly defined and therefore not calculated) for dichloroacetaldehyde, and - 1.45 volt,s for chloral hydrate. I n this paper, reference is made to the analysis of mixtures of chloral hydrate and either dichloro- or chloroacetaldehyde, but the experimental data show only mixtures of the three compounds. Because dichloro- and chloroacetaldehydes give coincident waves, the combination of the two compounds probably gives results similar to either of the individual aldehydes. Similarly, reference is made t,o chloral hydrate in this paper for chloral exists as the hydrate in aqueous solutions; a few runs in:& with chloral (anhydrous before dissolution) gave polarogrunis identical to those of chloral hydrate. The first and analytically usable wave of chloral hydrate falls between the first and second waves of the dichloro- and chloroacetaldehydes. To minimize the error of the near merging waves-Le., decrease of the plateau regions between waves as concentrations increase-it was advantageous to use standardized current increment.s over stated potential intervals. Reproducible rcvults wpre obtained for an aldehyde present. alone in borate huf-
1513 fer by using the current increment over the extrapolated babe bolution curve a t - 1.25 volts for dichloro- and chloroacetaldrhyde, and a t -1.65 volts for chloral hydrate. I n ammonia buffer, currents a t - 1.20 volts for dichloro- and chloroacetaldehydc, and a t - 1.60 volts for chloral hydrate lvere used. The currents thus obtained agree closely with those found by graphical construction. I n borate buffer good agreement with the current value for pure chloral hydrate solutions vas obtained for chloral hydrate in mixtures by subtracting the current increment a t - 1.20 volts (difference between limiting and extrapolated residual current) from that a t -1.60 volts compared to the extrapolated base solution; also for the combined concentrations of dichloro- and chloroacetaldehydes in mixtures the current value a t -1.20 volts was used (Table 11). In ammonia buffer, good agreement with the individual dichloro- plus chloroacetaldehyde current values was obtained for mixture3 by using the current a t -1.10 volts. The height of the second wave is not corrected for the effect of the electrocapillary curve owing to the method used for calculating the polarographic wave heights. Although the polarographic measurements can be madc a t any convenient temperature, it is essential that the calibration and sample measurements be made under the same conditions, because the currents produced by the chloroacetaldehydes are controlled by kinetic processes, and a slight change in temperature causes a large deviation in current. A constant teniperature arrangement for the polarographic cell, accuratc to 0.1" or 0.2", is satisfactory. ANALYTIC-4L 1'KOCEL)tiRES
Determination of One Chloroacetaldehyde Present Alone. Dilute a weighed or aliquot samplc with water, so that the 2 0 1 ~ t,ion is about 1 to 4 m M with respec+ to either dichloro- or chloroacetaldehyde or about 0.4 to 2.0 n i J l in the case of ch1or:tl hydrat'e. Dilute a portion of this stock solution-e.g., 25 nil.with an equal volume of ammonia buffer (ionic strength of 1.0, pH 8.4) or borate buffer (ionic strength of 1.0, H 9.2) (borate buffer is not suitable for the determination of d?chloroacet,altlehyde). Immediately transfer portions of the test solution to a polarographic cell maintained at a constant temperature-e.g., 25" =k 0.2" C.-and to the final bubbler of a nitrogen purging train. Pass nitrogen through the test solution for 10 minutes, then maintain the nitrogen atmosphere shove the solution during electrolysis. I'olarograph the solution between -0.5 and - 1.9 volts us. saturated calomel electrode. From the polarogram, measure t,hc current, increment over the est'rapolated base solution curve at -1.25 volts (boratc) or - 1.20 volts (ammonia) for dichloro- or chloroacetaldrhyde. :md at' -1.65 volts (borate) or -1.60 volts (ammonia) for chloral hydrate. Determine the concentration of the aldehyde from a standard series curve and calculate the amount originall>. p . i~~sent from the dilutions employed. Determination of Chloral Hydrate in the Presence of Either or Both Dichloro- and Chloroacetaldehvde. Dilute ii weighed or aliquot sample, so that the concentritions of chloral hyddrate and of the combined dichloro- and chloroa etaldehydes ale ahout 0.5 to 2.0 nidl. Dilute a portion of t'his olution with an equal volume of borate buffer, deoxygenate immediately, and ohtain a polarogram of the test solution. Subtract the effective current a t -1.20 volts (difference betn-cen limiting current and estrapolated residual current) from the effective current a t - 1.60 volts, and calculate the corresponding concentration of chloral hydrate from the standard series curve. Determination of Dichloro- or Chloroacetaldehyde in the Presence of Chloral Hydrate. Dilute :L iveighed or aliquot sample, so that thx concentration of chloral hydrate is about 0.4 m M or less, and the concentration of the dic1iloro- or chloroacetaldehyde is about 1.0 to 3.0 mill. Dilute a portion of this solution with an equal volume of ammonia buffer (borate buffer can be used for chloroacetaldehyde-chloral samples). Immediately deoxygenate and obt,ain a polarogram of the test solution. Ileasure the effective current a t -1.10 volts (ammonia) or -1.20 volts (borat'e), and calculate the corresponding concentration of dichloro- or chloroacetaldehyde from the standard series curves. In borat,e buffer, subtract the effective current a t -1.20 volts from the effective current a t -1.60 volts, and calculate the corresponding concentration of chloral hydrate from the standard series curve:.
1574
ANALYTICAL CHEMISTRY
TableiZI. Effect of Concentration on Polarographic Waves of Chloroacetaldehydes Compound'
Buffera
CIrCCH(0H)t
B
CIsCCH(OH)z
.4c
CliCHCHO
B
ClrCHCHO
A
ClCHaCHO
B
ClCHzCHO
.4
First Wave, pa. Mean Mean deviation 5.14 0.04 2.66 0.02 1.58 0.02 0.56 0.02 LO6 0.01 2.45 0.03 1.43 0.04 0.47 0.02 0.30 0.15
Concn.,
X o . of
1.00 0.500 0.300 0.100 1.00 0.500 0.300 0.100 1.72 0.860 0.430 1.72 0.860 0.430 0.258 2.00 1.00 0.500 0.300
3 3 3 3 3 3 3
3 2 3 2 3 3 3 2
0.08 0.75 0.38 0.20 0.13 1.28 0.65 0.32 0.20
0.01 0.01 0.01 0.02 0.03 0.01 0.01 0.00
2.00 1.00 0.500 0.300
2 3 3 2
1.05 0.52 0.26 O,l5
0.02 0.02 0.02 0.02
mM
Detns.
3
1 1 1
wave shapes and it is valid to correlate the concentration of dichloroacetaldehyde in terms of that of chloroacetaldehyde by use of the ratio of their wave heights. Thus, from Figure 1, approximately 3.7 parts (molar ratio) of dichloroacetaldehyde would behave similarly to one part of chloroacetaldehyde. The concentration ranges and probable accuracy of the analysis of mixtures are established on this basis. Analyzable Mixtures and Probable Accuracies. Because of the merging of the polarographic waves as the concentrations of the chloroacetaldehydes are increased and the coincident nature of the wavea of dichloro- and chloroacetaldehydes, it is necessary to maintain the concentrations of the individual compounds within certain limits in the final polarographic test solution, if satisfactory results are to be obtained. These concentration ranges, together with the probable accuracy of the results, are summarized in Table IV for both borate and ammonia buffers.
; DCAC
TGAc
and M CAc
Chloral hydrate, dichloroacetaldehyde, and chloroacetaldehyde. A. Ammonia buffer ( p H 8.4). B . Borate buffer ( p H 9.2). Chloral hydrate runs in ammonia buffer were made a t 60-cin. mercury head: all other runs were made at 80-cm. head.
2.50
0
b
e
DISCUSSION OF AYALYTIC4L RESULTS
Several sets of calibration data (concentration us. current) for the chloroacetaldehydes are given in Table I. The linear relationships obtained in borate buffer (Figure 1) show the large variation of current-concentration ratio among the aldehydes Figure 2 shows typical polarograms for a mixture of the chloroacetaldehydes in borate buffer. Tables I1 and I11 show the results of the determination of chloral hydrate in the presenre of the other rhloroacetaldehydes, and the determination of the combined rurrent of dichloro- and chloroacetaldehyde in mi\tures with chloral hydrate; the concentrations were calculated from the standard series data of Table I and Figure 1. Because of the nearly coincident E1 2 values and wave ihapes as well as similar currentconcentration ratios (the ratio of thr latter ratios is 0.85) of dichloro- and chloroacetaldehydes, the current produced from a mixture of the two may be conqidrred as behaving similarly to either individual compound. Thi. direct comparison is not valid in borate owing to the rehtivelv large difference in current-concentration ratios between the tn o compounds; however, the waves have similar E, 2 value\ and
1.5 0
0.50
Figure 1.
CONCENTRATION m M Standard Series Curves in Borate Buffer at pH 9.2
TCAc denotps rhloral hydrate, DCAc dichloioacetaldehyde, and MCAc chloroacetaldehyde
Table 11. Determination of Chloral Hydrate in Presence of Dichloro- and Chloroacetaldehyde in Borate Buffer and Determination of Current Produced from Combined Concentration of Dichloro- and Chloroacetaldehyde Sample Taken, m M ClCHaCHO ClzCHCHO CI,CCH(OH)z 0.300 0,602 o , zoo
0.200
0.602 0.860
0.200 0.200
0.700
Expected, pa.
0.30 0.56 0.28
1.00
0.860
0.200
0.79
0.500 0.200
0.430 0.172
0.200 0.200
0 40 0.16
0.700 0.200
0.602 0.172
0.700 1.00
0.56 0.16
0.500
0.430 0.860
1 00 1.00
0.40 0.79
1.00
a
Sum of currents produced by ClCHzCHO and ClzCHCHO.
First Waves Obtained. pa 0.31 0.29 0.32 0.54 0.30 0 29 0.79 0.76 0.42 0.20 0.21 0.65 0.48 0.48 0.70 1.17
_ Error _ ~ _ Expected, pa. 5% +0.01 3.3 -0.01 3 . 3 +0.02 6 . 7 -0.02 3.7 f0.02 7.2 + 0 . 0 1 3.G 0.00 0 . 0 -0.03 3.8 +0.02 5.0
b Large error of first wave at these concentrations is due to interference from chloral hydrate wave
pa 1.05 1.03 1.03 1.05 1.0; 1.05 3.64 5.15 5.15 5.15
Second Wave Obtained, ClzCCH(0H)X. Ma m .ll 1.03 0.195 1.02 0.193 1.04 0.198 1.00 0.190 1.08 0.205 1.10 0,208 1.10 0.208 1.07 0.203 1.06 0.202 1.00 0.190 1 .oo 0,190 3.60 0.693 5.09 0.990 5.16 1.00 5.03 0.977 5.24 1.02
Error m.Vl % -0.005 2 . 5 -0.007 3.5 -0.002 1.0 -0.010 5 . 0 +0.005 2 . 5 +0.008 4 . 0 +0.008 4.0 +0.003 1 . 5 f0.002 1 . 0 -0.010 5.0 -0.010 5.0 -0,007 1.0 -0.010 1.0 0.00 0.0 -0,023 2.3 io.020 2.0
V O L U M E 26, N O . 10, O C T O B E R 1 9 5 4
1575
Table 111. Determination of Current Produced from Combined Concentration of Dichloro- and Chloroacetaldehyde in Ammonia Buffer ClCHtCHO 1 .oo 0,200 0 . so0 0,700 0.500 0.500 1.00 0.500
Sample Taken, m.M C h C H C H O CllCCH(OH), 0.172 0,200 0.200 0.860 0,200 0.602 0.200 0.602 0,200 0.430 0,500 0.430 1.00 0.172 1.00 0.430
Current Expected, pa. ClCHzCHO CllCHCHO 0.52 0.03 0.11 0.38 0.16 0.26 0.38 0.25 0.26 0.19 0.26 0.19 0.52 0.03 0.26 0.19
Samples which contain the aldehydes in relative concentration 1 anges outside those shown could perhaps be handled by adding one or more of the aldehydes in known amount, to bring the test solution concentrations within the desirable magnitudes. Possible Interferences. I n general, interference would be expected from polarographically active substances, whose waves fell in appreciable amount in the region of -1.0 to 1.7 volts. ilretaldehyde would interfere if present in large amounts but it would be largely removed during the nitrogen stripping of the test solution. Small amounts of acetaldehyde might possibly be estimated from the combined acetaldehyde wave by deducting the contributionfi due to the chloroacetaldehydes.
Total 0.55 0.49 0.41 0.63 0.45 0.45 0.55 0.45
Current Obtained, pa. Total 0.54 0.48 0.42 0.64 0.44 0.47 0.67 0.61
Error pa. -0.01 -0.01 +0.01 +0.01 -0.01
%
1.9 2.0 2.4 1.6 2.2 +0.02 4 . 4 + 0 . 1 2 22 + 0 . 1 6 36
ACKNOWLEDGMENT
The authors wish to thank the Atomic Energy Cornmiskion which supported the work described. LI'I'ERATURE CITED
Adams, W. L., J . Pharmacol., 74, 11 (1942). Andron, P., Bull. soc. pharm. Bordeauz. 64, 199 (1926). Andron, P., J . pharm. chim.,(8) 8 , 453 (1928). Brugeas, C., Bull. soc. pharm. Bordeaux, 66, 12 (1928). Ibid., p. 78. Elving. P. J . , and Bennett, C. E.. J . Electrochem. Soc., in press. Federlin. P., C o n ~ p t .rend., 232, 60 (1951). Fialkov, Y. A , , and Etinger, 11.I., Parniatsiya i Farmakol., 1937, N o . 8, 6; Chem. Zeutr.. 1938, I, :3237. Fluery, P., and IIalmy, ll.,J . pharril. chin., (8) 8 , 537 (1928). Ibid..(7) 16, 269 (1917). Fraiicois, M., Ibid.,(8) 7, 54 (1928). Freidman, 11.AI., arid Calderoiie, F. .\.. J . Lab. Clin. M e d . , 19, 1332 (1934). Gamier, J., Bull. sci. pharmacolog., 15, 77 (1908). Goretskii, L. &I.,Farmatsiya, 1940, No. 6, 31. Griffon, H., Mossanen, N . , arid Ligault-Demare, J . , Ann. pharm. franG., 7, 578 (1949). Harrington, T., RoJrd, T. H., arid Cherry, G. W., Analyst, 71, 97 (1946). Khait, G. Y., V k r a i n . Gosudavsl. I ~ a s t Eksptl. . Farm. (Kharkov), Iionsul'tatsio?~nyeMaterialy, 1939, No. 3, 80. Kolthoff, I. M.,P h a r m . Fi'eekhlad. 60, 2 (1923). Iiomyathy, J. C., Alalloy, F.. a n d Elving. P. J., AXAL.CHEM., 24,431 (1952). Lormand, C., J . pharm. c h t m . , (6) 9, 151 (1929). U l l a t i u , A. I., Pouescu, A, and Petrescu. E., Bull. w a d . m4d. R o u m a n i e , 14,598 (1943). 1 Meillere, G., .I. p h a l m . chim.. ( 8 ) 11, 14.5 (1930). I I Aleyer, V.,and Haffter, H.. B e r . derrt. chem. Ges., 6, 600 (1873). Slitchell. J., Jr., and Smith, L). SI., ANAL. CHEM..22, 746 -0.80 -L 20 -160 (19.50). POTENTIAL,V. Xeiinan, AI. B., Ryabov, A. T., and Sheyanova. E. 11..Doklady A k a d . S a u k S.S.S.R., 6 8 , 1065 (1949). Figure 2. Polarogranis of a Mixture Olsaxcka. I.. Bull. soc. chiin. b i d . , 19. 731 (1937). (27j Hai&ez, C., Reo. q u i n ~ .6, , S o . 10, 6 (1931). 0.200 n1.V chloral hydrate, 0.172 m.M dichloroacetaldkhgde and 1.00 m M chloroacetaldehyde in borate buffer ( p H 9.2, ionic strength (28) Rogers. L. J., TTans. Rou. SOC.C a n . , (3) 17, Section 111, 164 of 0.40 and 80-om. mercury head). I and I1 are duplicate runs; (1923). I11 and I V are duplicate runs of same solution a t higher sensitivity. (29) Rupp. E., Pharm. Zentraliiaiir, 64, 151 (1'323). I shows extraprlated residual current (dashed line) (30) Sadtler. S. Y., Lathrop. E. C., and Rlitchell, C . A , , "hllen'a Commercial Organic Analysis," 5th ed., Philadeluhia. P. Blakiston'a Son 6 Co., Inc., 1923. Table IV. Applicability of Polarographic ,Method to Determination (31) Schwicker. A , , Z . a d . Chem.. 110, 161 (1937). of Individual Chloroacetaldehydes and Analysis of Mixtures (32) Self. P. A. W., Ph.arm. J.. (4) 25, 4 (1907). (33) Snell. F. D., and Riffen, F. AI., "Commercial Relative Concn. Range Permissible Probable Precidon, Relative % .\lethods of Analysis," New York, McGrawClCHaCHO, ClzCHCHO, ClaCCH(OH)z, rn ,M rn M m 24 ClCHzCHO ChCHCHO ClsCCH(0H) ' Hill Book Co., Inc., 1944. (34) Tsisina, G. V., and Al'shits, &I. I., Farm. Zhur., Borate Buffer 1937, KO. 1, 43. 0.5-2.0 0 0 3 ... .. (35) "U. S . Pharmacopoeia," 11th ed., Easton, Pa., 0.2-1.0 ... . . 2 0 0 Mack Printing Co., 1950. 0.5-1.5 0 0.2 4. ... 3 0.2-1.0 0 . 2 - 1 .o 0.2-1.0 ... 3 (36) Tan der .\leulen. J. H.. Chem. Weekblad, 45, 91 (1949). Ammonia Buffer (37) Wallis, T. E., Pharrn. J., (4) 22, 162 (1906). (38) Watson. H. A., A m . J . Pharm., 102, 606 (1930). 0 0 5-2 0 0 0 c (39) Weston, F. E., and Ellis, H. R.. Chem. News, 95, 0.9-1.5 0 210 (1907). 3 ... 0 0 9-1 5 0 2 ~
R E C E I V Efor D review M a y 1 , 1954.
hccepted July 26, 1954.
