CAPILLARY ELECTROPHORETIC DETERMINATION OF AMINO-ACIDS WITH INDIRECT ABSORBENCY DETECTION

Methods for the capillary electrophoretic (CE) analysis of a mixture of twenty common amino acids with indirect absorbance detection were developed. The suitability of nine background electrolytes (BGEs) was investigated. The effects on the CE separation of the analytes of the BGE, pH, and various additives were evaluated. Metal cations and cationic surfactants were used as buffer additives either to decrease or to reverse the electroosmotic flow in order to improve the resolution. p-Aminosalicylic acid and 4-(N,N-dimethyl)aminobenzoic acid are best suited as the carrier buffers and background absorbance providers as they have effective mobilities closer to the mobilities of most amino acids at alkaline pH. The CE separation of 17-19 amino acid peaks could be achieved in 20-40 min. The performance of CE in various BGEs and the influence of pH, divalent metal ions and cationic surfactants are discussed.