Development and validation of a stability-indicating HPTLC-Densitometric method for satranidazole

A sensitive, selective, precise, and stability-indicating high performance thin layer chromatography (HPTLC) method for analysis of satranidazole both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene/acetonitrile (60:40, v/v). Densitometric analysis of satranidazole was carried out in the absorbance mode at 314 nm. This system was found to give compact spots for satranidazole (R-f value of 0.53 +/- 0.02, for six replicates). Satranidazole was subjected to acid and alkaline hydrolysis, oxidation, and photo degradation. The drug undergoes degradation under acidic and basic conditions, oxidation, and photo degradation. Also, the degraded products were well resolved from the pure drug with significantly different Rf values. The method was validated for linearity, precision, limit of detection (LOD), limit of quantitation (LOQ), and accuracy. Linearity was found to be in the range of 100-500 ng/spot with a significantly high value of correlation coefficient r2 = 0.9979 +/- 0.66. The LOD and LOQ were 50 and 85 ng/spot, respectively. Statistical analysis proved that the method is repeatable and specific for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of the alkali degradation process.