Application of ion-pair complexation reaction for the spectrophotometric determination of bupropion hydrochloride in pharmaceuticals.

This is the first report on the use of visible spectrophotometry for the determination of bupropion hydrochloride (BUPH), a second-generation antidepressant, in pharmaceuticals. Two sensitive, selective, and cost-effective spectrophotometric methods are described. The first method (method A) is based on the formation of yellow-coloured ion-pair complex between the BUPH and methyl orange (MO) at pH 3.80 ± 0.10 which was extracted into dichloromethane and the absorbance measured at 425 nm. The second method (method B) is based on the breaking of the yellow BUPH-MO ion-pair complex in acid medium followed by the measurement of the red-pink colour at 520 nm. Beer's Law is obeyed over the concentration ranges of 1.00-12.0 and 0.48-7.20 µg ml(-1) BUPH for method A and method B, respectively. The molar absorptivities are calculated to be 2.18 × 10(4) and 3.79 × 10(4) l mol(-1) cm(-1) for method A and method B, respectively, and the corresponding Sandell sensitivity values are 0.0127 and 0.0073 µg cm(-2) . The limits of detection and quantification have also been reported. The proposed methods were applied successfully to the determination of BUPH in pure drug and commercial tablets. The accuracy and reliability of the proposed methods were further ascertained by recovery studies via standard addition technique.