INVESTIGATIONS ON NITROGEN COMPOUNDS AND NITROGEN METABOLISM IN PLANTS. II. VARIABLES IN TWO-DIRECTIONAL PAPER CHROMATOGRAPHY OF NITROGEN COMPOUNDS: A QUANTITATIVE PROCEDURE

Abstract

The variables involved in the chromatography of amino compounds as applied to their quantitative detn. have been studied. These include the purity of paper, the purity of solvents, the rate and distance of solvent movement, temp. and saturation of atmosphere to paper. The variables are so controlled that losses of amino acids during chromatography are the same on each chromatogram. The amino acids may, therefore, be detd. quantitatively by a colorimetric method utilizing the reaction of ninhydrin on paper. The quantitative procedure has been tested by recovery of added amino acids from a potato extract. In 10 of 12 amino compounds loss was 5% or less, and in 2 others, less than 10%. The method has been applied to the analysis of a casein hydroly-sate and the results compared with published data showing the composition of this protein and the results are in close agreement. The method can now be used for the quantitative analysis of such mixtures of amino acids as occur free in plants or may be expected to arise from hydrolysis of protein. The method is applicable to amts. of total N of the order of 50-100 [mu]g.