A Enantio-selective and chemo-selective HPLC method for the determination of Abacavir Sulfate and its enantiomer

Abstract

An accurate, simple and reproducible high-performance liquid chromatographic (HPLC) method has been developed and validated for the direct separation of individual enantiomers of Abacavir sulfate, a nucleoside reverse transcriptase inhibitor for the treatment of HIV, in pharmaceutical bulk drugs. The enantiomers were resolved by normal phase chromatography, on Chiralpak IA column by using a mobile phase with selective composition of Hexane-Ethanol-Methanol-Diethylamine (DEA) (600:250:150:0.1; v/v/v/v).  Diethylamine, the mobile phase additive played a very significant role in improving the chromatographic resolution and also in enhancing chromatographic efficiency, with in 20.0 min runtime. Baseline separation of the enantiomers of Abacavir was obtained with a resolution greater than 4. The developed method was extensively validated and proved its suitability and robustness. The developed method was found to be selective in the presence of its degradation products, generated from forced decomposition studies. The standard curves for the two enantiomers were linear (r > 0.999) in the concentration range from 0.06 µg/mL (LOQ) to 2.0 µg/mL for an analyte concentration of 0.5 mg/mL for each enantiomer. The percentage recovery of (R)-Abacavir was ranged from 99.3 to 100.6 in bulk drug samples of Abacavir. The limit of detection and limit of quantitation for (R)-Abacavir were 0.02 µg/mL and 0.06 µg/mL respectively. The intra-day precision (%RSD) results were 2.5 and 2.4, while the inter-day precision results were 3.8 and 2.6 calculated for area response of (R) and (S)-Abacavir, respectively. Abacavir sample solution stability and mobile-phase stability were studied for 48 h and found to be stable during the period. The validated method yielded good results of selectivity, linearity, precision, accuracy and robustness, and was also able to resolve the enantiomers from the USP listed impurities of Abacavir sulfate.