Stripping voltammetric quantification of the anti-diabetic drug glipizide in bulk form and pharmaceutical formulation

The electrochemical behavior of glipizide at the hanging mercury drop electrode (HMDE) was studied in B–R universal buffers of pH 1.7–11. The voltammograms exhibited a well-defined 4-electron irreversible cathodic peak which attributed to reduction of the two CN double bonds of the pyrazine ring of glipizide molecule. Glipizide was found to has an interfacial adsorptive character onto the mercury electrode surface. A monolayer surface coverage of 1.02 × 10−10 mol cm−2 was estimated and hence each adsorbed glipizide molecule occupied an area of 1.63 nm2 onto the mercury electrode surface. A simple and precise square-wave adsorptive cathodic stripping (SWAdCS) voltammetric procedure was described for quantification of bulk glipizide with a limit of detection of 1.5 × 10−10 M and a limit of quantitation of 5 × 10−10 M. The proposed procedure was successfully applied for quantitation of glipizide in its pharmaceutical formulation (Minidiab tablets) without interference from excipients.