Quantitative Estimation of Eszopiclone in Bulk and in Formulation by Simple UV and Difference Spectroscopic Methods

Two simple efficient, precise and accurate simple UV and difference spectroscopic methods have been developed for the estimation of Eszopiclone in bulk and in pharmaceutical dosage form. In method A, UV Spectra of Eszopiclone in 0.1M Hydrochloric acid exhibits the absorption maximum 304 nm. Method B is based on the measurement of difference in absorbance of Eszopiclone at maxima 307 nm and minima at 239 nm. The measured value is the amplitude of maxima minima between two equimolar concentrations of the analyte in different chemical forms, which exhibits different spectral characteristics. Beers law limit the concentration range of 3–18 μg/ml for method A, and method B, for 2–12 μg/ml. The accuracy of the method was determined by recovery studies. The methods were validated statistically. The methods showed good reproducibility and recovery with % RSD less than 2. The methods were found to be simple, economical, accurate and reproducible and can be used for routine analysis of Eszopiclone in bulk drug and in formulation.