Rapid Method for Quantitative Deterxninatiw of Carbon in Organic Compounds C. B. POLLARD AND W. T. FORSEE,JR., University of Florida, Gainesville, Fla.
T
HIS method was s u g g e s t e d by the work of Adams ( I ) , but the differences are evident from Figure 1. A built-in d r o p p i n g funnel allows the addition of the o x i d i z i n g m i x t u r e (2) without o p e n i n g t h e flask. The carbon dioxide is determined gravimetrically. An aspirator is used to pull air through the apparatus.
through from 1 to 2 hours. This length of time has been found ample for all compounds used and in most cases this was shortened a great. deal, depending upon the rapidity of oxidation. For cooling the flask neck, a slow stream of compressed air may be directed upon it. This will allow more rapid heating and thus shorten the time required for complete oxidation. Satisfactory and consistent checks with the theoretical percentage of carbon have been obtained when using various types of organic compounds. The results of a few of the carbon determinations by this method are shown in Table I. This method has been satisfactorily used in these laboratories for the past 2 years by students of quantitative organic analysis and in organic research. TABLE I. ANALYSESOF COMPOUNDS CARBON THEORETICAL FOUND CARBON DIFFERENCE
SUBBTANCE ANALYZED
nzso,
CA C L ~
Cerium phenylacetate Thiocarbanilide a-Nitrobenzoio acid Diazoaminobenzene Piperazoniumphenylacetate Oxalic acid
A3CABITf
FIGURE 1. DIAGRAM OF APPARATUS The procedure is similar to that of any other wet oxidation. Before admitting the oxidizing mixture, disconnect the aspirator and close the intake at E . Pour 10 cc. of the oxidizing solution into the dropping funnel A , and admit this into the flask. (Keep the stem of the funnel h l of liquid at all times during the determination,) Immediately admit 30 to 50 cc. of the acid mixture. Heat the flask with a very small flame (about 1.25 em. proceed immediately without high). In some cases oxidation heating. The amountof heating mustbe gaged by the rate of oxidation of the sample. After the oxidation becomes slow, connect the aspirator, increase the heating, and allow air to pass
%
%
51.19 68.35 50.29 73.02
51.22 68.36 50.29 73.05 67.00 19.04
66.98
19.00
0.03 0.01
0.00 0.03 0.02 0.04
ACKNOWLEDGMENT The authors express their appreciation to J. E, Adams and R- M. Barnette for valuable suggestions. LITERATURE CITED (l)Adams, J. E., I N D OE N G . CHEM.9 h a l . Ed., 63 277 (1934). (2) ASSOc. Official Agr. Chem., Official and Tentative Methods Analysis, 3rd ed., p. 4 (1930).
Of
RECBIVED dugust 11, 1934
Effect of Asparagine on the Reducing Power of Levulose IONEWEBER,EDNA J. POSEN,AND NEDDAG. CEBOOLSKY, Brooklyn College, Brooklyn, N. Y. TABLEI. EFFECTOF ASPARAGINE
A
STUDY of the effects of nitrogen compounds on the determination of sugars by copper reduction methods has been undertaken. Xtrogen compounds, principally asparagine and aspartic and glutamic acid, are present in raw sugar sirups. Non-glucose-reducing substances are present in blood and urine. The determinations reported in Table I are on levulose in the presence of asparagine. Levulose supplied by the Bureau of Standards and Eimer and Amend asparagine c. P. were used. The volumetric method of Jackson ( I ) , modified to the extent of evaporating the nitric acid solution of cuprous oxide almost to dryness and dissolving the residue in water, was used for most of the determinations. The result reported in each case is the average of two to four determinations. The difference between the result for asparagine plus levulose and the result for levulose alone in each case is within the experimental error. The proportion of asparagine to levulose in the above experiments is very much greater than the proportion in blackstrap (commercial raw sirup). The conclusion can be drawn that the presence of asparagine does not affect the determination of levulose by the Nijns method a t 49' C.
COPPER SUGAR
Ma, 20
i!
20 0 35
335535
0 35
i! 3; 50 50 50 50 5
AsPARAGINE
Mg.
AVERAGE
Mg.
0 12
65.3 65.1
1s
65.4 1.0 114.0 112.9 111.9
15 18 0 8 10 12
10 0 8 10 12 10
0 12 15 18
67.6
110.3
0.5
112.1'" 110.7a 109. o'i 109.10 1.4a 163.1 102.1 162.1
162.6
DEVIATKW FROM SUGAR BLANg
DEVIATION OF ANALYBTS
Ma.
Mo
... 0.2 2.3 0.1 ... ...
1.1 2.1
3.7
...
... 3.1 1.4
3.0
...
...
1.0 1.0 0.5
.
2.7 1.9 1.4
1.8
...
0.6 2.6 3.5 1.8
...
7.5
8.7
5.2 8.5 I
t
.
3.8
3.6 1.0
2.9 Reaults obtained by the gravimetric method using Nijna solution ( 8 ) .
LITERATURE CITED (1) Jackson, J . , J . A ~oficiaz ~ Agr. ~ Chem., ~ 12,166 . (1929). (2) Zerban, F. W., and Sattler, L., IND.ENQ.CHEM.,And. Ed., 2, 307 (1930). RECEIVED June 16, 1934.
77
