Amino acid analysis by HPLC: optimized conditions for chromatography of phenylthiocarbamyl derivatives

A method for analysis of phenylthiocarbamyl-amino acids by HPLC is described. Solvent A contains 0.05 M sodium acetate plus triethylamine (2.75 ml/liter) adjusted to pH 6.40 with phosphoric acid. Solvent B consists of 50% solvent A, 40% acetonitrile, and 10% methanol. The stationary phase is a 3-micron Spherisorb ODS-2 column (4.6 X 100 mm). A new sample can be injected every 27 min. Variation of the triethylamine concentration from 1 to 4 ml/liter is shown to affect column selectivity in a predictable manner, and this provides a rational basis for optimizing chromatographic conditions. Resolution of certain hydrophilic amino acids (Arg, Thr, Ala, and Pro), and mobile phase stability are improved over previously described procedures.