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Development of a high-performance liquid chromatography method for the simultaneous determination of chiral impurities and assay of (S)-clopidogrel using a cellulose-based chiral stationary phase in methanol/water mode.

A simple reversed-phase high-performance liquid chromatography method for the chiral separation of the active pharmaceutical ingredient (S)-clopidogrel has been developed on the cellulose-based Chiralcel OJ-RH chiral stationary phase. The S enantiomer was baseline resolved from its R impurity (impurity C) with a mobile phase consisting of methanol/water (100:15) without any interference coming from the other two potential chiral impurities A and B. The enantio- and chemoselective method was partially validated and compared with that reported in the United States Pharmacopoeia for the drug product. The versatility of the Chiralcel OJ-RH allowed separating the enantiomers of the impurity B also under normal phase and setting up an efficient strategy to convert the racemic sample into the enantiomeric S form on a semipreparative scale.