A Reliable Fluorescence Method of One-Pot Condensation for Sensitive Determination of Epinastine in Aqueous Humor: Greenness, Blueness, and Redness Assessment.

Epinastine used in treatment and management of allergic conjunctivitis. The development of a simple, sensitive, and cost-effective analytical method for its quantification is essential for pharmaceutical quality control and study. Green (eco-friendly) spectrofluorimetric method for the determination of epinastine in ophthalmic preparations and aqueous humor samples was developed. The method involves converting the cited drug into a fluorescent derivative through a one-pot condensation reaction with fluorescamine, which serves as a detection probe. Fluorescamine is a reagent that reacts specifically with the primary amine moiety of epinastine, forming a highly fluorescent product. In borate buffer (pH 8.5), the reaction yielded a fluorescent product with maximum emission intensity at 483 nm upon excitation at 390 nm. The fluorescence intensity showed a linear response within the concentration ranges of 60-400 ng/mL and 65-350.0 ng/mL for standard epinastine and spiked aqueous humor samples, respectively. The method demonstrated high sensitivity, with limits of detection (LOD) of 19.5 and 20.60 ng/mL and limits of quantification (LOQ) of 59.11 and 62.50 ng/mL for standard epinastine and aqueous humor samples, respectively. The greenness profile of the method was evaluated using four smart metric tools.