Development and Validation of a Green Spectrofluorimetric Method for Nateglinide Quantification: Utilizing AR87 as a Probe With Box-Behnken Optimization and Quantum Mechanical Calculations.

In this study, a sensitive and selective spectrofluorimetric method was developed for the determination of the antidiabetic drug nateglinide based on its reaction with the xanthene dye acid red 87 (AR87). A fluorescence quenching process was observed for the AR87 at 545 nm upon the addition of nateglinide, which was exploited for the quantitative analysis. The reaction mechanism was investigated using quantum mechanical calculations suggesting a transfer between the electron-rich AR87 and the electron-deficient nateglinide. Additionally, the stoichiometry of the interaction was determined through Job's method revealing a 1:1 nateglinide-AR87 complex formation. The experimental parameters were optimized using a Box-Behnken design of experiments, including pH, reagent concentration, and buffer volume. The optimized method was validated according to ICH guidelines, demonstrating excellent linearity in the range of 0.1-3.0 μg/mL, with a detection limit of 0.0320 μg/mL and a quantitation limit of 0.0961 μg/mL. Furthermore, the greenness and blueness of the method were assessed using the AGREE and BAGI indices, indicating an environmentally friendly procedure. The developed method was successfully applied for the determination of nateglinide in pharmaceutical dosage forms and spiked human plasma samples posing a promising analytical tool for clinical and quality control applications.