Spectrophotometric determination of metformin in pharmaceutical preparation (tablets) and environmental water samples: Application to content uniformity testing


Abstract A simple, accurate, and rapid visible spectrophotometric method has been developed for the determination of metformin in pure form, pharmaceutical preparations and environmental water samples . The method is based on the reaction of metformin with copper in alkaline solution in the presence of citrate ion to form a violet colored chromogen with an absorption maximum at 570 nm. Beer’s Law was obeyed in the range of 10-100 µg/ml with molar absorbitivity and Sandell,s sensitivity of 1.656×103 L.mol.-1.cm-1 and 0.1 µg/cm2 respectively. The relative standard deviation of the method was less than 2% and accuracy (average recovery ) was 100±1.4% .The optimum conditions for color development are described and the proposed method has been successfully applied for the determination of metformin in pharmaceutical preparations and water samples. The common excipients and additives did not interfere in the proposed method.