Spectrophotometric determination of metformin in pharmaceutical preparations,serum and urine using benzoin as derivatizing reagent

A simple and selective spectrophotometric procedure is described for the determination of metformin based on derivatization with benzoin. the beer’s law was obeyed with 2.50-12.50 μmol l^⁻1 at 290 nm with coefficient of determination (r^2) 0.997. the experimental conditions in term of ph, reaction time and temperature, and addition of derivatizing reagent were examined. the pure metformin-benzoin derivative was prepared and characterized by ft-ir and mass spectroscopic techniques. the method was applied for the determination of metformin from pharmaceutical preparations and serum and urine of volunteers after spiking with metformin. the results were checked by standard addition method. a number of pharmaceutical additives and serum or urine matrix did not affect the determination of metformin.