Determination of Free Histidine in Complex Hair Care Products with Minimum Sample Preparation Using Cation-Exchange Chromatography and Post Column Derivatization.

In this communication, we describe the first analytical method for the determination of free histidine in hair care products (shampoos and conditioners). Cation-exchange chromatography combined with postcolumn derivatization and fluorimetric detection enabled the accurate (recovery: 83.5-114.8%) and precise (2.4-5.6% RSD) determination of free histidine without matrix interferences at concentration levels down to 1.5 mg kg-1. Real commercially available samples were found to contain the amino acid at levels ranging between 70 and 535 mg kg-1.