Development of a sustainable fluorescence-based approach using erythrosine B dye for nanolevel quantification of bepotastine in eye drops and aqueous humor

This study presents an innovative spectrofluorimetric methodology for the environmentally friendly and highly sensitive quantification of Bepotastine (BTT), a second-generation antihistamine used in allergy treatment. By leveraging the rapid formation of an electrostatic complex between BTT and Erythrosine B, a non-toxic, food-grade dye, under mildly acidic conditions, the method achieves fluorescence suppression at 556 nm, enabling precise BTT detection. Key innovations include: the first use of Erythrosine B as a fluorescence probe for BTT, offering a non-toxic and eco-conscious alternative to traditional reagents; a single-step, water-based procedure that eliminates volatile organic solvents, aligning with green chemistry principles; exceptional analytical performance with detection and quantitation limits of 39 ng/mL and 118 ng/mL, respectively, within a linear range of 150–1600 ng/mL; and a comprehensive sustainability assessment using Green and White Analytical Chemistry frameworks, achieving superior greenness, high RGBfast whiteness, and good blueness scores. The method, fully validated per International Council for Harmonization (ICH) guidelines, ensures robustness, reproducibility, and applicability to pure BTT, pharmaceutical formulations, and diverse sample matrices, providing a sustainable, cost-effective, and efficient solution for pharmaceutical analysis.