Flow Injection Photosensitized Chemiluminescence of Luminol with Cu(II)-Rose Bengal: Mechanistic Approach and Vitamin A and C Determination

Rose Bengal photosensitized flow injection chemiluminescence method is reported using luminol-Cu(II) for the determination of vitamins A and C in pharmaceutical formulations. The reaction is based on the enhancement effect of analyte in the production of anion radicals of Rose Bengal (RB(•−)) which rapidly interact with dissolved oxygen and generate superoxide anions radicals (O(2) (•−)) and hydrogen peroxide (H(2)O(2)). Highly reactive hydroxyl radicals ((•)OH) were produced via dismutation of H(2)O(2) by catalyst (Cu(2+)). The generated superoxide anions radicals and hydroxyl radicals thus oxidize luminol in alkaline medium to generate strong chemiluminescence. The limit of detection (3s of the blank, n = 6) of vitamins A and C and RB was found to be 0.008, 0.005, and 0.05 μg mL(−1), respectively. The sample throughput of 70 h(−1) for vitamins A and C and 30 h(−1) for RB was found. Calibration curve was linear in the range of 0.05–15, 0.01–20, and 0.1–50 μg mL(−1) for vitamins A and C and RB, respectively, with relative standard deviations (RSDs; n = 3) in the range 1.6–3.6%. The method was successfully applied to pharmaceutical formulations and the results obtained were in good agreement with the labeled values.