In this work two simple, economical, and rapid spectrophotometric methods have been selleckchem Imatinib established for the quantification of entacapone in bulk material and in tablets. The developed methods were validated for accuracy, precision, ruggedness, and sensitivity. Accordingly, the objective of this study was to develop and validate the simple spectrophotometric method for the estimation of entacapone hydrochloride in bulk and tablets as per ICH guidelines.[10] MATERIALS AND METHODS Materials Entacapone was a gift sample from Wockhardt Pharmaceuticals, Aurarangabad. All chemicals and reagents used were of analytical grade and purchased from Qualigens Fine Chemicals, Mumbai, India. Instrument A double beam UV-VIS spectrophotometer (UV-2450, Shimadzu, Japan) connected to computer loaded with spectra manager software UV Probe with 10 mm quartz cells was used.

The spectra were obtained with the instrumental parameters as follows: Wavelength range: 200�C500 nm; scan speed: Medium; sampling interval: 1.0 nm. All weights were taken on an electronic balance (Model Shimadzu AUX 120). Preparation of stock standard solution and selection of wavelengths A stock standard solution was prepared by dissolving 10 mg of entacapone in a 100 mL of 10% v/v acetonitrile to obtain a concentration of 100 ��g/mL. From it, an appropriate concentration of 10 ��g/mL was prepared and scanned in the UV-visible range 500�C200 nm; entacapone showed a maximum absorbance at 384.40 nm. In Method I, area under curve (AUC) of the zero-order spectrum was recorded between the 348.00 and 410.20 nm.

While, in Method II, zero-order spectra were derivatized into first-order and the AUC was recorded between 386.40 and 460.20 nm. Validation of the method Study of linearity curves From the stock standard solution, an appropriate amount of aliquots portion in the range of 0.2�C1.2 mL were transferred into a series of 10 mL volumetric flasks and diluted up to mark using the same solvent to obtain a concentration in the range of 2�C12 ��g/mL. The solutions were scanned on a spectrophotometer in the range of 500�C200 nm. The calibration curves were plotted concentrations versus AUC between 348.00 nm and 410.20 nm (Method I). While in Method II, an appropriate amount of aliquots portion in the range of 0.5�C3.0 mL were transferred into a series of 10 mL volumetric flasks and diluted up to the mark using the same solvent to obtain concentration in the range of 5�C30 ��g/mL. The calibration curve Carfilzomib was plotted as concentration versus AUC between 386.40 and 460.20 nm (Method II). Recovery studies To the pre-analyzed sample solutions, a known amount of stock standard solution was added at different levels, i.e. 80%, 100%, and 120%. The solutions were re-analyzed by the proposed methods.