Abstract

A novel, simple, and selective indirect spectrofluorimetric method was developed for the quantitative determination of captopril (CPL) and clopidogrel bisulfate (CLO) in both bulk materials and pharmaceutical formulations. The method is based on the fluorescence quenching of 4,5-dibromo fluorescein (DBF) at 540 nm (λex = 330 nm) caused by the formation of non-fluorescent ion-pair complexes between DBF and the studied drugs. The decrease in fluorescence intensity (ΔF) showed a linear correlation with drug concentration in the ranges of 0.4–14 μg/mL for CPL and 0.4–8 μg/mL for CLO. The method demonstrated high accuracy, with mean recoveries of 99.7% and relative standard deviations ranging from 1.11 to 4.12%. Application to commercial tablets confirmed the suitability of the method, with results in excellent agreement with certified values and those obtained by the standard addition technique. Common pharmaceutical excipients did not interfere with the assay. Owing to its simplicity, sensitivity, and lack of prior extraction steps, the proposed method represents a practical alternative to more complex and solvent-intensive techniques.

Keywords: spectrofluorimetry, captopril, clopidogrel bisulfate, 4,5-dibromofluorescein

Article language: En.