Optimum combination of reversed-phase column type and mobile-phase composition for gradient elution ion-pair chromatography of amino acids

An optimum combination of reversed-phase column type and eluent composition was selected for the practical separation of amino acids by gradient elution ion-pair chromatography. A butyl-silica (C4) column with a concentration gradient elution between 5 mM SDS-10 mM HClO4 solution and acetonitrile provided the best resolution for amino acids. The C4 column was most adequate for reducing the chromatographic cycle time including the column regeneration. The use of 5 mM SDS as ion-pairing agent in relatively low concentration is economical and practical for replicate and routine analyses. The developed HPLC system is applicable to the analysis of organic cations at low cost.