DETERMINATION OF ASPARAGINE, GLUTAMINE AND CITRULLINE IN AQUEOUS SOIL EXTRACTS WITH AN AUTOMATIC AMINO ACID ANALYZER

Abstract

A system of separating asparagine, glutamine and citrulline from each other and from the other common amino acids, using lithium buffers and the Technicon amino acid analyzer and C2 resin in a 0.63 × 75-cm column, is described. The column was operated with a buffer flow rate of 37 ml/hour at 30 °C for the first 70 min, then at 50 °C. The buffer was 0.067 M in lithium citrate and adjusted to a pH of 2.80; 2% isopropanol was added to improve the separation of threonine and serine. The analysis was complete through citrulline in 4 hours. If a second buffer, pH 4.15, 0.25 N in lithium was added after 3.5 hours, most of the common acidic and neutral amino acids found in soil extracts were separated in 6 hours. Some data on the determination of asparagine and glutamine by amide hydrolysis is included.