LC Separation of para and meta Isomers of Zafirlukast in Bulk Drug Samples and Pharmaceutical Dosage Forms Using a Chiral Stationary Phase

A simple, rapid and sensitive high performance liquid chromatographic method was developed for the separation and quantification of positional isomers of zafirlukast in bulk drugs and dosage forms using a chiral column. Elution time was 20 min in normal phase mode and ultra violet detection was carried out at 240 nm. Efficient separation was achieved on an immobilized amylose-based Chiralpak-IA column using n-hexane/ethanol/trifluoroacetic acid/diethyl amine (65:35:0.1:0.1, v/v) as the mobile phase. Resolutions between ortho, meta and para isomers of zafirlukast were found to be >3.0. The active pharmaceutical ingredient was extracted from tablets using tetrahydrofuran. The calibration graphs for meta and para isomers of zafirlukast were linear (r ² > 0.999) when ranging from the limit of quantitation to 0.3%. The method showed excellent recoveries for both zafirlukast isomers identified in bulk and formulated products. The test solution was found to be stable in the mobile phase for 48 h after preparation. The developed LC method was validated with respect to linearity, accuracy, precision and robustness.