1976 Volume 25 Issue 8 Pages 514-518
Amino acids react with salicylaldehyde to yield their Schiff's bases in alkaline solution, and the Schiff's bases-Cu(II) chelates formed by the addition of Cu(II) ion are extractable with MIBK in the presence of bathophenanthroline. Therefore, amino acids can be determined indirectly by the estimation of copper in the organic phase by atomic absorption spectrophotometry. Two ml of (2.0×10-52.0×10-4) M amino acid solution, 2.0 ml of 1.0×10-2 M salicylaldehyde solution, 1.0 ml of 1.0×10-3 M cupric acetate solution and 5 ml of boric acid buffer solution of pH 10.0 were taken into a 30 ml centrifuge tube and mixed sufficiently. After the solution was allowed to stand for 5 minutes, 10.0 ml of chloroform was added. The mixture was shaken for 10 minutes and was centrifuged. After separation, 5.0 ml of the upper aqueous phase was transferred into another 30 ml centrifuge tube and 10.0 ml of 1.0×10-4 M bathophenanthroline MIBK solution was added. Being shaken well for 5 minutes, it was centrifuged and the copper in organic phase was determined by atomic absorption spectrophotometry.
The optimum pH range was found to be 9.511.5. On the determination of glycine, the linear relationship was found between the absorbance and the concentration in the range of (1.515.0) μg/ml and the standard deviation and the coefficient of the variation were 0.71 and 1.45% respectively and the recovery was 99.8%. This method is applicable to the quantitative determination of amino acids such as glycine, valine, phenylalanine, tyrosine, tryptphan and methionine.
