STABILITY INDICATING METHOD DEVELOPMENT AND VALIDATION OF REVERSE PHASE ULTRA-FAST LIQUID CHROMATOGRAPHY METHOD FOR SIMULTANEOUS ESTIMATION OF SITAGLIPTIN PHOSPHATE AND METFORMIN HCL IN BULK AND TABLET DOSAGE FORM

A RP-UFLC method was developed &validated for simultaneous estimation of Sitagliptin Phosphate and Metformin HCl in bulk and tablet dosage form. Separation was achieved by using Phenomenex Luna C18 (150 × 4.6mm, 5µm) column. The mobile phase comprises MeOH: Phosphate Buffer of pH 7 using Triethylamine in the ratio (60:40v/v). The flow rate was 0.6ml/min at temperature 300C. The instrument used for UFLC was Shimadzu autosampler separation model LC 20AD. Quantification was achieved with UV detection using a photodiode array detector at 258nm wavelength. The injection volume was 20µl. The retention times of Sitagliptin Phosphate & Metformin HCl were found to be 7.027 & 2.802, respectively. The linearity range of Sitagliptin Phosphate was 50-100µg/ml & Metformin HCl was 10-60µg/ml. The correlation coefficient was found to be within limits, i.e., 0.999. The % purity of Sitagliptin Phosphate & Metformin HCl was found to be 101.99% and 101.73%. LOD values were found to be 2.21437 for Sitagliptin Phosphate & 1.99084 for Metformin HCl and LOQ values were found to be 6.71024 for Sitagliptin Phosphate & 6.03286 for Metformin HCl. % RSD of both the drugs were found within the acceptance criteria, i.e., ˂2. Forced degradation studies were also performed to check the stability of the drugs under acidic, basic, oxidation, thermal, photolytic conditions.