The use of complex formation approach for spectroscopic analysis of certain oral hypoglycemic with Eosin Y

Abstract

Validated, simple and cost effective spectrophotometric and spectrofluorimetric methods were developed for the assay of vildagliptin (VLD), saxagliptin (SAX) and sitagliptin (STP) in dosage forms. The main principle of these methods is binary complex formation through the reaction of the drugs amino group with Eosin Y (EY). The studied drugs were determined spectrophotometrically at 542 nm in acetate buffer of pH 4.4 for VLD and SAX and pH 4.0 for STP. The studied drugs were further determined spectrofluorimetrically by measuring their quenching effect on the EY native fluorescence at 545 nm after excitation at 302 nm. The absorbance-concentration graphs were rectilinear over the ranges of (30–250), (10–160) and (5–100) μg mL−1 for VLD, SAX and STP, respectively. The fluorescence-concentration graphs were rectilinear over the ranges of (0.4–3.0, 0.25–1.0 and 0.1–1.0) μg mL−1 for VLD, SAX and STP, respectively. By studying the effect of temperature on the quenching process, and, according to the Stern–Volmer plots, the quenching of EY fluorescence was concluded to be static in nature. The suggested methods have been validated according to ICH guidelines and were successfully applied for the analysis of commercial tablets containing the studied drugs. The results were in good agreement with those of the reference methods as there was no significant difference regarding the accuracy and precision.