Spectrophotometric multicomponent analysis of a mixture of chlorhexidine hydrochloride and lidocaine hydrochloride in pharmaceutical formulation using derivative spectrophotometry and partial least-squares multivariate calibration

Abstract

Two spectrophotometric methods were applied to the simultaneous assay of chlorhexidine hydrochloride ( CHL ) and lidocaine hydrochloride ( LIH ) in pharmaceutical formulations. Using derivative spectrophotometry, CHL was determined by measurement of its first derivative signal at 290 nm (peak to zero amplitude) in the concentration range 5–9 μg/mL, and LIH was analysed by measurement of its second derivative signals at 272 and 276 nm (peak to peak amplitude) in the concentration range 160–480 μg/mL. With the partial least-squares (PLS-2), the experimental calibration matrix was constructed using 9 samples. The concentration ranges considered were 5–7 μg/mL for CHL and 220, 240, 260 μg/mL for LIH. The absorbances were recorded between 240 and 310 nm at every 5 nm.