A Sustainable Photochemical Strategy Based on a “Fluorescence On–Off” Mode for Nanoscale‐Quantitative Analysis of Brexpiprazole in Different Matrices: Tablet Uniformity Evaluation

A new green spectrofluorometric method was developed for the sensitive and accurate determination of brexpiprazole (BXZ), a newly approved antipsychotic for schizophrenia. The method relies on ion-pair complex formation between BXZ and Aizen Food Red 3 (AFR 3) dye. The method monitors the natural fluorescence of AFR 3 dye, excited at 530 nm with emission at 550 nm, which is quenched upon ion-pair complexation with BXZ. Experimental parameters for optimizing the BXZ-AFR 3 complex formation were thoroughly investigated. The fluorescence quenching showed a linear response to BXZ concentrations from 150.00 to 1800.00 ng/mL. The method demonstrated excellent sensitivity, with limits of detection (LOD) and limits of quantification (LOQ) of 47.92 ng/mL and 145.21 ng/mL, respectively. The method's reliability and accuracy were confirmed through the study of the method's validation following ICH guidelines, making it suitable for assessing the uniformity of the BXZ in its pharmaceutical formulations. The method's environmental impact was comprehensively assessed using several tools. Additionally, its overall "whiteness" and "blueness" were evaluated using the innovative RGB12 and BAGI ranking systems. This multifaceted approach not only ensures precise BXZ quantification but also establishes a new benchmark for sustainable analytical chemistry in pharmaceutical research and quality control.