The terminal peptides of insulin

Abstract

While this work was in progress an outline of a fluorimetric method for the determination of N- methyl-2-pyridone-5-carboxylamide in urine was reported by Rosen, Perlzweig & Handler (1948). The authors considered that their values for normal urines (5.0-13.2 mg./day) may have been somewhat low, but it is obvious that they are of the same order as those obtained by the present colorimetric method (see Table SUMMARY 1. Methods are described for the determination of N-methyl-2-pyridone-5-carboxylamide and N- methyl-2-pyridone-3-carboxylamideinhuman urine. The methods are based on the nitration of the com- pounds, after isolation from urine by adsorption on Lloyd's reagent followed by extraction with chloro- form, and on their colorimetric determination by means of the yellow colours given by the nitro derivatives in alkaline solution.