Abstract
A double isotope-dilution method of analysis for the determination of amino acids in protein hydrolysates obtained from small samples of proteins with acetic anhydride labeled with C14 and H3 is described. The method was applied to synthetic mixtures of amino acids and to the 72 hour hydrolysates obtained from 2 [mu]g of 2 proteins of known composition, namely the fraction A peptide of oxidized insulin and whole insulin. Values are given for the analysis of chymotrypsinogen and these are compared with the results obtained by microbiological assay and by column chromatography.