Development and validation of stability-indicating high-performance thin-layer chromatography method for estimation of sitagliptin phosphate monohydrate in bulk and in pharmaceutical formulation

A simple, selective, precise, and stability-indicating high-performance thinlayer chromatographic method for analysis of sitagliptin phosphate both in a bulk and in pharmaceutical formulation has been developed and validated. The method employed high-performance thin-layer chromatography (HPTLC) aluminium plates precoated with silica gel 60 RP-18 F254 as the stationary phase. The solvent system consisted of methanol-water-triethylamine (8:2:0.05 v/v). The system was found to give compact spot for sitagliptin phosphate (Rf value of 0.55 ± 0.03). Densitometric analysis of sitagliptin phosphate was carried out in the absorbance mode at 267 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.998±0.0015 with respect to peak area in the concentration range 1000–6000 ng per spot. The mean value ± SD of slope and intercept was 0.723 ± 0.043 and 17.24 ± 18.78 with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 85.80 and 265.42 ng per spot, respectively. Sitagliptin phosphate was subjected to acid and alkali hydrolysis, oxidation, and photo and thermal degradation. The drug undergoes degradation under acidic, basic, and oxidative conditions. This indicates that the drug is susceptible to acid and base, and oxidation. The degraded product was well resolved from the pure drug with significantly different RF value. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of investigated drug. The proposed developed HPTLC method can be applied for identification and quantitative determination of sitagliptin phosphate in bulk drug and pharmaceutical formulation.