Unlocking delafloxacin fluorescence with 9-fluorenyl methyl chloroformate: A sensitive spectrofluorimetric method for pharmaceutical and plasma analysis with greenness and whiteness assessment

BACKGROUND: A highly sensitive spectrofluorimetric method was developed for the determination of delafloxacin based on fluorescence derivatization with 9-fluorenyl methyl chloroformate (FMOC-Cl). The derivatization reaction was performed at room temperature in borate buffer (pH 8.0), producing a strongly fluorescent derivative suitable for sensitive quantitative analysis. RESULTS: The formed fluorescent derivative exhibited maximum excitation and emission wavelengths at 264 and 314 nm, respectively. We systematically investigated and optimized experimental parameters affecting the derivatization reaction and fluorescence response. The proposed method showed good linearity over the concentration range of 5.0-100.0 ng mL⁻¹, with a correlation coefficient of 0.9994. The limits of detection and quantification were 1.25 and 3.81 ng mL⁻¹, respectively. The method demonstrated satisfactory accuracy and precision, with a mean recovery of 101.43% ± 0.64. The applicability of the method was successfully confirmed through the determination of delafloxacin in pharmaceutical preparations and spiked human plasma samples. Statistical comparison with a reported reference method showed no significant difference between the results. The environmental performance of the proposed method was additionally assessed using the Carbon Footprint Reduction Index (CaFRI) and White Analytical Chemistry Evaluation (WECA), demonstrating favorable analytical and environmental characteristics. CONCLUSIONS: The proposed fluorescence derivatization method provides a sensitive, precise, and accurate approach for determining delafloxacin in pharmaceutical and spiked plasma. Its favorable analytical performance and environmental assessment support its potential application in routine pharmaceutical quality control and bioanalytical investigations.