1h qnmr approach for estimation of a toxic compound n,n-dimethylamine in metformin hydrochloride: an equivalent efficient method over reversed phase derivatization hplc method

a rapid, specific and accurate proton quantitative nuclear magnetic resonance spectroscopic (1h qnmr) and also a reversed phase derivatization hplc method have been developed to quantify a toxic, uv-visible inactive and non-volatile impurity n,n-dimethylamine hydrochloride (dma∙hcl) in metformin hydrochloride (mf∙hcl), an active pharmaceutical ingradient. the method is based on proton quantitative nmr spectroscopy (1h qnmr) using glycine as internal standard and deuterium oxide (d2o) as diluent. both the methods have been validated as per the parameters of ich guidelines and are found to be comparable.the advantages of the proposed 1h qnmr method are that no certified reference standard of dma∙hcl is required for quantification, the method is specific, non-destructive and can be applied for quantification of dma∙hcl in process, quality control for the manufacturing of metformin hydrochloride as well as commercial dosage form products.