SPECTROPHOTOMETRIC METHOD FOR DETERMINATION AND KINETICS OF AMINO-ACIDS THROUGH THEIR REACTION WITH SYRINGALDEHYDE

A spectrophotometric method is described for the determination of amin o acids. The method is based on the reaction between amino acids and s yringaldehyde at pH 9.0, by which a color is developed with maximum ab sorption at 420 nm in aqueous methyl alcohol. The absorption of the pr oduct obeys Beer's law within the concentration range of 0.025-0.5 mM of original amino acid. The kinetics of the reaction follows overall s econd order kinetics, first order in each of the reactants. The rates of the reaction were investigated as a function of pH of the reaction medium and structure of the amino compounds. Logarithms of the second- order rate constants increased with amino acid anion concentration as the pH was increased. The mechanisms of the reaction have been discuss ed. (C) 1998 Elsevier Science B.V.