An eco-friendly HPTLC method for assay of eszopiclone in pharmaceutical preparation: investigation of its water-induced degradation kinetics

An eco-friendly, sensitive and selective high-performance thin-layer chromatographic method was developed and validated for analysis of eszopiclone in bulk powder and formulation. The method employed HPTLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of methanol-water (6 : 4, v/v). Densitometric analysis of eszopiclone was carried out at 300 nm. This system was found to give a compact spot for eszopiclone (R-f value of 0.48 +/- 0.02). The proposed method was validated for linearity, precision, robustness, LOD, LOQ, specificity and accuracy in accordance with ICH guidelines. Linearity was found to be in the range of 0.2-1.2 mu g per band with a significantly high value of correlation coefficient r = 0.9997. Statistical comparison with a reported reference method showed similar results with respect to accuracy and precision. The study of the eszopiclone water-induced degradation kinetics was carried out by the proposed HPTLC method. The activation energy and degradation rate constant at room temperature were calculated after the construction of the Arrhenius plot.