[High performance liquid chromatographic enantiomer separation of beta-blocking agents with a new isothiocyanate type chiral derivatizing agent].

The applicability of (1R,2R)-1,3-diacetoxy-1-(4-nitrophenyl)-2-propyl isothiocyanate [(R,R)-DANI] as a recently developed chiral derivatizing agent for the enantioseparation of a series of beta-blockers is described. The thiourea diastereomers formed were analysed by reversed-phase high-performance liquid chromatography, mixtures of water and methanol or acetonitrile being used for elution. Conditions of derivatizations (temperature, reagent excess and reaction time) were optimized. The effects of organic modifiers on the retention and separation were investigated; the diastereomers could readily be baseline-separated with methanol-containing mobile phases. The reagent allowed the detection of all four stereoisomers of labetalol, which has two chiral centres.