Colorimetric Determination of Long-chain N-Acylglutamic Acids with Pinacyanol

Abstract

A new colorimetric method for the quantitative microanalysis of long-chain N-acylglutamic acids is proposed. This method consists of two steps in which a pinacyanol derivative derived from a long-chain N-acylglutamic acid and pinacyanol dye is extracted with an organic solvent, and the color intensity of the extract is spectrophotometrically measured. Long-chain N-acylglutamic acids were found to react speifically with pinacyanol chloride to form their pinacyanol derivatives under a weakly acidic condition. These derivatives were extracted with chloroform and determined by measuring the absorbancy of the solution at 610mμ within the range of 0.01_??_0.15mg. Several factors affecting the analysis and standard procedure of the determination were also investigated.