Development and validation of an enantioselective and chemoselective HPLC method using a Chiralpak IA column to simultaneously quantify (R)-(+)- and (S)-(−)-lansoprazole enantiomers and related impurities

An accurate and reproducible high-performance liquid chromatographic (HPLC) method has been developed and validated for the direct separation of individual enantiomers of lansoprazole, a potent proton pump inhibitor belonging to the family of the substituted benzimidazoles. The enantiomers were resolved on a Chiralpak IA by using a mobile phase consisting of methyl-tert-butyl ether (MtBE)–ethyl acetate (EA)–ethanol (EtOH)–diethylamine (DEA) in the ratio 60:40:5:0.1 (v/v/v/v). Baseline separation of the enantiomers of lansoprazole was obtained with a resolution factor of 8.14. The standard curves for the two enantiomers were linear (r2 > 0.999) in the concentration range of 10–80 μg/ml with a working concentration of about 60 μg/ml for each enantiomer. Apparent recovery was 100.8% with a relative standard deviation less than 2%. The limit of quantization for each enantiomer of lansoprazole was 0.22 μg/ml. The intra-day precisions were in the range of 0.21–0.36 and 0.59–0.66 while the inter-day precisions were in the range of 0.55–1.24 and 0.66–1.19% in terms of retention times and area response RSD% for (R)-(+)- and (S)-(−)-lansoprazole, respectively. The method was also able to resolve impurities from the enantiomers of lansoprazole.