New Colorimetric Methods for the Estimation of Abacavir Sulphate in Bulk and Dosage Forms

Author(s): B. Rajitha, S. Prashanthi, K. Ram Subha Reddy, S. K. Gulati and G. Tuljarani

Four simple, sensitive, rapid and accurate visible spectrophotometric methods (designated as A, B, C and D) have been developed for the estimation of abacavir sulphate in pharmaceutical formulations. Methods A and B are based on the ion pair complex formation of abacavir sulphate with dyes erichrome black -T and orange–G in acetate buffer followed by their extraction with chloroform. The absorbance of organic layer was measured for the above complexes at 510 nm and 484 nm, respectively. Method C is based on oxidative coupling between abacavir sulphate and 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in presence of cerric ammonium sulphate (CAS) to form a colored product with absorption maxima at 630 nm. Method D is based on the oxidation/reduction reaction between the abacavir sulphate and Folin-ciocalteau reagent (F.C. reagent) to form blue color chromogen having absorption maxima at 752 nm. All the variables have been optimized. The concentrations of measurements are reproducible within a relative standard deviation of less than 1% .The linearity was found to be 5 to 60, 2.5 to 15, 10 to 50 and 10 to 70 µg/mL for method A, B, C and D, respectively. The proposed methods were validated statistically. Recovery studies were carried out by standard addition method.

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