Van Slyke method

Carbon was estimated by a variation of the Van Slyke method.(2) A 30-100 mg sample was heated for 30 minutes with 0.5 g K2Cr207, lg KIOj, 10 mL 20% fuming H2S01( and 5 mL HjPO in a closed flask swept by a purified N2 stream. The N2 stream carried the evolved C02 to an absorption solution of 0.5M Na0H-0.3M N H. After the wet combustion, the absorbed C02 was released from an aliquot of the NaOH solution with lactic acid in a manometric apparatus. Corrections were applied for the vapor pressure of water and for reagent blank. 

The improved methods introduced in the years 1940 to 1945 created new possibilities in this field. The Van Slyke method for quantitative determination of amino acids, based on the measurement of the volume of carbon dioxide evolved in the course of the reaction between amino acids and ninhydrin (V2), was much more reliable than the older methods. At the same time the microbiological methods designed for amino acid determinations (D3, S6) made possible the detection of very small concentrations of these compounds. The application of these... 

Problem 21.20 Many a-amino acids react with MONO to give a quantitative volume of N, (Van Slyke method of analysis). Which amino acids in Table 21-1 cannot be analyzed by this method A... 

Problem 21.47 Among the hydrolysis products of the pentapeptide Gly,Ala,Phe are Ala.Gly and Gly.Ala. Give two possible structures if this substance gives no N, with HONO (Van Slyke method). -4... 

The purity of the recrystallized DL-aspartic acid was established by nitrogen analysis by the Kjeldahl and Van Slyke methods. The decomposition point of this product is 325-348°. 

A common biological determination is for amino-acid nitrogen. This determination is made by the van Slyke method, in which the amino groups (-NH2) in protein material react with HN02 to produce N ga< volume of which is measured. A 0.530 g sample of a biological material containing glycine,... 

Carbon was estimated by a variation of the Van Slyke method.( ) A 30-100 mg sample was heated for 30 minutes with 0.5 g K2Cr20y, Ig KIO, 10 mL 20% fuming H2S0 and 5 mL in a closed flask swept... 

Polymers. Poly (L-leucine) and poly( -benzyl-D-aspartate) were kindly provided by E. M. Bradbury, Portsmouth Polytechnic. Poly(L-alanine), poly(D-alanine), and poly(L-methionine), MW 40,000, were obtained from Sigma Chemical Co. A further sample of poly(L-methio-nine), MW 36,000, (Van Slyke method) was obtained from Mann Research Labs. Poly( -benzyl-L-aspartate), MW 210,000, poly(c-benzyl-oxycarbonyl-L-lysine), MW 400,000, poly (c-benzyloxycarbonyl-o-lysine), MW 900,000, poly(y-n-decyl-L-glutamate), MW 860,000, and poly(y-benzyl-D-glutamate), MW 235,000, were all obtained from Pilot Chemicals. The remaining polymers were the same as those used previously (12, 14). 

Fraenkel Conrat, H. Effect of Light in the van Slyke Method for the... 

An advantage of GC methods over the classical Van Slyke method consists in elimination of the errors related to the presence in a gas mixture of nitrogen and other gaseous compounds [110—112] which are not absorbed by alkaline potassium permanganate solution and lead to overestimated results. 

Biotin was found to have the empirical formula C10H16O3N2S. The electrometric titration showed that it was a simple monocarboxylic acid with a neutralization equivalent of 244. The hydrolysis yielded an optically active diamino-carboxyhc acid which had the composition C9H18O2N2S. It contained two primary amino groups as established by the Van Slyke method and could be reconverted to biotin by treatment with phosgenes. ... 

The results have shown that the Van Slyke method can measure... 

Imino group Manometric Van Slyke method [7,11] Hydrazinolysis [36, 37] Z c... 

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