Microanalysis of Amino Acids. III. Modified Ninhydrin Reagent for Use in a Quantitative Determination by Paper Partition Chromatography (Supplement).

Abstract

A Ninhydrin reagent for use in the quantitative determination of amino acids separated by paper partition chromatography was worked out. It was confirmed that the best concentration of the reagent is 0.5%. The reagent had to be added with ascorbic acid as 1% solution in metaphosphoric acid if the optical density of the blank test was not to exceed 0.04∼0.05 (log I⁰/I). The blank test value was 0.04 (log I⁰/I) or less when the reagent to be used in paper partition chromatography was kept in alkaline state by the addition of sodium hydroxide and left standing overnight in a reduced pressure over sulfuric acid in a desiccator before it was used. Amino acid spotted at a concentration of 0.08∼0.4 mμM/cc. was recovered quantitatively within the error of 5%.