REVERSED-PHASE LIQUID CHROMATOGRAPHY WITH MASS DETECTION AND NMR CHARACTERIZATION OF SITAGLIPTIN DEGRADATION RELATED IMPURITIES

The current work on impurity profiling of Sitagliptin in its bulk drugs, included development of a stability- indicating reverse-phased liquid chromatographic method and its validation for the estimation of degradation related impurities (DRIs). Sitagliptin was subjected to acid and alkaline hydrolysis, H₂O₂ oxidation, thermal degradation and photolysis. Acid hydrolysis and H₂O₂ oxidation yielded significant degradants, which were isolated on a semi-preparative high performance liquid chromatography (HPLC) and characterized with the help of high-resolution mass spectrometry, ¹H-NMR spectroscopy. Possible structures of the DRIs were reveled with the help of mass measurement and NMR spectroscopy. The chromatographic separations were accomplished on Waters Cosmosil C₁₈ column (250 mm x 4.6 mm; 5 µm) using 5mM ammonium acetate and methanol as a mobile phase with gradient elution at 1.0 ml/min flow rate, and eluents were detected using photo diode array detector at 268 nm wavelength. The method was validated with respect to accuracy, precision, linearity, robustness, and limits of detection and quantification as per International Conference on Harmonization (ICH) guidelines.