The estimation of glutamine in the presence of asparagine

Abstract

A reaction time of 10 min. in the Van Slyke apparatus gave only 49.5% of the total N of asparagine, but 92% of that of glutamine. The stability of asparagine, glutamine, and other substances in solution at 100[degree] at various pH values was observed by determining both amide-N and amino-N. Asparagine was quite stable over the range pH 4-8, while large amounts of amide-N were given off from glutamine at pH 3, 4, 5, 8, 9, and 10. With 3 hrs. heating at 100[degree] at pH 8, glutamine gave 35% of the total N as amide-N, while asparagine was stable under these conditions. Advantage of this difference in behavior was taken in developing a method for the separate determination of these 2 substances in plant extracts.