A Validated Stability Indicating Reverse Phase Liquid Chromatography Method for Metformin HCL and its Impurities in Bulk and Pharmaceutical Dosage Form

A simple and stability indicating liquid chromatographic method was developed for the determination of purity of metformin hydrochloride drug substance, drug product in bulk samples and pharmaceutical dosage form in the presence of its impurities and degradation product. The mobile phase used consisted of Buffer: acetonitrile (90:10 %v/v) with pH 3.6 (adjusted with 0.006M phosphoric acid) and flow rate 1.0ml/min in isocratic mode. The separation was carried out by UV detector at wavelength 218nm using Inertsil ODS 3V (250 mm X 4.6mm id, 5 μ) column. This new method was validated in accordance with USP requirements for new methods for assay determination, which include accuracy, precision, specificity and linearity. The current method demonstrates good linearity over the range of 50 to 200% of metformin hydrochloride. The accuracy of the method was found to be from 97.11 to 98.36%. The precision of this method reflected by relative standard deviation of replicates was found to be 0.27%.Validation of the same method for impurities determination was also performed according to USP requirements for quantitative determination of impurities which include accuracy, precision, linearity, selectivity and limit of quantification.