Use of Eco-friendly Brominating Agent for the Spectrophotometric Determination of Carbamazepine in Pharmaceutical Formulations

We describe two sensitive spectrophotometric methods for the determination of carbamazepine (CBZ) either in pure form or in pharmaceutical formulations. These methods are based on the bromination of CBZ by the bromine generated in situ from the bromate-bromide reaction. The methods involved the addition of a known excess of bromate-bromide reagent in acid medium to CBZ. After the reaction was complete, the unreacted bromine was determined by reacting with a fixed amount of either fluorescein sodium (FS) and measuring the absorbance at 510 nm (method A) or with rosaniline hydrochloride (RAH) and measuring the absorbance at 570 nm (method B). Beer’s law was obeyed in the concentration ranges of 0.45–3.00 µg/mL of CBZ with molar absorptivity of 5.37×104L/mol/cm for method A and 0.50–3.50 µg/mL of CBZ with molar absorptivity of 5.19×104L/mol/cm for method B. The proposed methods were successfully applied to the determination of CBZ in tablets and syrup with good accuracy and precision and without detectable interference from common excipients. The validity and reliability of the proposed methods were further assessed by the recovery studies via a standard addition method. These methods have the advantages of avoiding the use of liquid bromine and offering cost-effective analyses