An improved method for the microdetermination of arginine by use of 8-hydroxyquinoline

Abstract

The color formed by the reaction of arginine with 8-hydroxyquinoline in the presence of hypobromite is stabilized by extraction with butanol, and the use of urea avoided. A study of variables that may interfere in the reaction is presented, and the optimum conditions for performing the test are established. The amount of hypobromite necessary to avoid interference by protein hydrolysates is determined. The reaction allows quantitative determination of arginine between 0.5 and 6 ug/ml; the color is stable for at least 12 hours. Results are constant and reproducible (standard deviation [plus or minus] 1.3%).