Utility of certain π-acceptors for the spectrophotometric determination of gliclazide and tolazamide
The reaction of gliclazide and tolazamide with three selected π-acceptors in acetonitrile-water (9 + 1) at pH 9.0–9.5 was found to give intensely coloured products. A method based on this reaction is proposed for the determination of trace amounts of both drugs. Quantification was carried out at 445 nm for p-chloranil, 450 nm for p-bromanil and ca. 750 nm for 7,7,8,8-tetracyanoquinodimethane. The molar ratios of the reactants were established and the experimental conditions giving maximum absorption were also studied. The proposed procedures were applied successfully to the determination of both drugs either in pure samples or in tablets with good accuracy and precision. The results were compared with those obtained by the official USP method.