The present work describes three spectrophotometric methods for determining two phytoconstituent berberine hydrochloride and eugenol in formulated gels: simultaneous equation method, absorbance correction, and zero-crossing derivative method. In the simultaneous equation method, the absorbance at 263 nm and 280 nm and the absorbance correction method at 345 nm and 280 nm were measured and applied to their respective equation for the estimation of berberine hydrochloride and eugenol in phosphate buffer and formulated emulgel. The amplitudes of the first derivative spectra were measured at 252.5 nm for berberine hydrochloride and 263.5 nm for eugenol in zero-crossing crossing derivative spectrophotometry. For berberine hydrochloride and eugenol, linearity was attained in the concentration ranges of 4–20 and 2–10 μg/ml, respectively. Validation shows the applicability of the above procedures for the quantitative determination of berberine hydrochloride and eugenol. As a result, the presented method sucessfully estimated the aforesaid active phytoconstituent in formulated emulgel, with no interference from excipients.
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