A novel green synchronous spectrofluorimetric platform for ultra-trace simultaneous determination of letrozole and bicalutamide in pharmaceutical, biological, and environmental matrices

Abstract

The increasing occurrence of pharmaceutical residues in biological and environmental matrices has created a demand for sensitive, selective, and sustainable analytical methods for their determination. Letrozole (LTR) and bicalutamide (BCL), two non-steroidal anticancer drugs co-administered for the treatment of testotoxicosis, exhibit native fluorescence; however, their emission spectra significantly overlap, preventing their direct simultaneous determination. In this work, a green synchronous spectrofluorimetric method was developed to overcome this limitation by improving spectral resolution through synchronous scanning of the excitation and emission monochromators. Under the optimized conditions (Δλ = 50 nm), LTR and BCL were directly quantified at 240 and 272 nm, respectively, without prior separation or derivatization. The proposed method showed linear responses over concentration ranges of 0.5–150.0 ng mL−1 for LTR and 5.0–1000.0 ng mL−1 for BCL, with limits of detection of 0.09 and 1.29 ng mL−1, respectively. The method was validated according to ICH guidelines and demonstrated satisfactory accuracy, precision, selectivity, and reproducible analytical performance. Its applicability was confirmed by the simultaneous determination of both analytes in pharmaceutical formulations, spiked human plasma and urine, and environmental water samples, providing satisfactory recoveries with minimal matrix interference. In addition, the method requires minimal solvent consumption and avoids hazardous reagents, and its environmental sustainability was confirmed using the Analytical Green Star Area (AGSA) and Multi-color Assessment (MA) tools.