Spectrophotometric method for the determination of dobutamine hydrochloride

Abstract

A rapid, accurate and simple method is proposed for the determination of dobutamine hydrochloride in the bulk drug and in vials. This method is based on measuring the intensity of the pink colour that develops when dobutamine hydrochloride is allowed to react with thiosemicarbazide in an alkaline - acetone medium. The colour is stable for at least 3 h and can be quantified spectrophotometrically at 510 nm (ε_max.= 1.7 × 10⁴ l mol^–1 cm^–1). Beer's law is obeyed in a concentration range 0.5–20 µg ml^–1 in the final assay solution. The effects of reagent concentration, alkali concentration and solvent on colour formation were investigated. A Job's plot of absorbance versus the molar ratio of dobutamine to thiosemicarbazide indicates a 1 : 1 ratio. As the catecholic group with free adjacent positions is required for colour development, the method is highly specific.