A simple steam distillation method of estimating β-hydroxy-α-amino acids

Abstract

A simple steam distillation method of estimating β-hydroxy-α-amino acids from the ammonium released by their reaction with alkaline periodate is described. It involves steam distillation with phosphate-borate buffer (pH 11.2) before and after treatments with periodic acid (to oxidize β-hydroxy-α-amino N to ammonium N) and with sodium arsenite (to reduce excess periodate), the ammonium liberated by the second distillation being determined by titration of the distillate with standard acid. The method is rapid and precise, and it gives quantitative results with serine, threonine, and other β-hydroxy-α-amino acids. When applied to protein hydrolyzates, it gives results in close agreement with those obtained by the periodate method of estimating β-hydroxy-α-amino acids proposed by Van Slyke, Hiller, and MacFadyen.