Background
The presented quadruple divisor spectrophotometric method was able to resolve and analyze a complex quintuple drug matrix with severe overlapped spectra without previous separation or extraction steps or need of complicated apparatus like chromatographic methods and had the advantage of being green as the solvent used was water.
Method
Simple, sensitive and precise quadruple devisor spectrophotometric method was developed for simultaneous determination of metformin, glipizide, and sitagliptin in presence of metformin potential impurities melamine and cyanoguanidine. The proposed method was applied for analysis of metformin, glipizide, and sitagliptin in pure form and pharmaceutical formulation (tablets). The developed method was validated and met the requirements for ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness.
Results
A linear response was observed in the range of 2-27, 2-20, 1-20, 0.5-10, and 1-10 μg/mL for metformin, glipizide, sitagliptin, melamine and cyanoguanidine, respectively with a correlation coefficient of 0.9996 and 0.9998, 0.9997, 0.9997 and 0.9996 for metformin, glipizide, sitagliptin, melamine and cyanoguanidine, respectively.
Conclusion
The validated method was successfully applied for determination of the studied drugs in Janumet® and Engilor® tablets; moreover the results were statistically compared to those obtained by the reported RP-HPLC method and no significant difference was found between them; indicating the ability of proposed method to be used for routine quality control analysis of these drugs.