S-trityl-(R)-cysteine, a powerful chiral selector for the analytical and preparative ligand-exchange chromatography of amino acids.

S-trityl-(R)-cysteine [(R)-STC] is the new selector of a dynamically coated, chiral ligand-exchange stationary phase which proved to be highly effective in both analytical and preparative-scale separation of enantiomers of some natural and unnatural underivatized amino acids, with good separation and resolution factors. With the aim of identifying the best chromatographic conditions suitable for the preparative-scale separations, some parameters controlling retention, separation and resolution factors (such as the type and amount of cupric salt and the eluent pH) were investigated. The relatively easy removal of the Cu(II) ions renders this technique suitable for obtaining small amounts of enantiomerically pure samples for preliminary biological evaluations.