FLUORIMETRIC DETERMINATION OF CARBOCISTEINE AND ETHIONAMIDE IN DRUG FORMULATION
Mohamed I. Walash,* Amina M. El-Brashy, Mohamed E.-S. Metwally, and Amina A. Abdelal
Chemistry Department, Faculty of Pharmacy,
A highly sensitive and specific fluorimetric method was developed for the determination of carbocisteine and ethionamide in their dosage forms. The proposed method based on the reaction of carbocisteine and ethionamide with roth's reagent (o-phthaldehyde) to get a highly fluorescent isoindole product emits strong fluorescence at 431 nm and 424 nm after excitation at 329 nm and 339 nm for carbocisteine and ethionamide, respectively. The thiol group present in these compounds is responsible for the formation of highly fluorescent complexes of improved stability and enhanced fluorescence. The different experimental parameters affecting the intensity of the fluorescence were carefully studied and incorporated into the procedure. Under the described conditions, the method was applicable over the concentration range of 0.05-0.9 mg/mL and 0.25-2.5 mg/mL with detection limits of 5 ng/mL and 26 ng/mL for carbocisteine and ethionamide, respectively. The proposed method was successfully applied for determination of carbocisteine and ethionamide in their dosage forms.
Key words: flourimetry, o-phthaldehyde, carbocisteine, ethionamide, dosage forms