Concentration of Amino Acids with Mixed Hydroxide of Iron(III) and Copper(II)

Abstract

Amino acids are adsorbed on a mixed hydroxide of iron (III) and copper (II) at about pH 9and desorbed at above pH 13. The adsorption-desorption process of amino acids was studied in detail using tyrosine as a sample and the 50-fold concentration of tyrosine was adsorbed from its solution as low as 2x 10^-6 mol/l with the recovery of 96%. A suspension of the mixed hydroxide, which was prepared by mixing 10 ml of 1.0 mol/l iron (Jn) chloride and 10 ml of 1.0 mol/l copper (II) chloride, diluting the mixture to 100 ml with distilled water, and pre cipitating mixed hydroxide with sodium hydroxide, was added to 1 / of a sample solution containing 2 X10^-6 - X 10^-7 mol/l tyrosine. After adjusting the pH between 8.5 and 9.5, and the mixture was stirred for 40 min. The suspension was separated through filter paper (No.5C, φ 7 cm) under suction. The residue was dried at 100°C in an oven. Twenty milliliters of 0.5 N sodium hydroxide was added to the dried residue and stirred for 15 min. The recovery of tyrosine was determined spectrophotometrically with 1-nitroso-2-naphthol. The proposed method was applied to the concentration of other amino acids. The recoveries of amino acids were determined by the Ninhidrin method.