Zinc (II)‐Chelation‐Enhanced Spectrofluorimetric Determination of Moxifloxacin: Development, Validation, Application to Eye Drops, and Greenness Assessment

A sensitive and straightforward spectrofluorimetric method was developed for determination of moxifloxacin (MOX) based on its complexation with zinc ion (Zn2+) in acetate buffer (pH 5). A formation of the MOX-Zn chelate produced a pronounced fluorescence enhancement, measured at 487 nm after excitation at 287 nm. Experimental conditions influencing the fluorescence response, including metal ion type and volume, buffer system, pH, diluting solvent, and reaction time, were optimized. Under the optimized conditions, the calibration curve exhibited excellent linearity over 10.00-70.00 ng mL-1 with a correlation coefficient of 0.9997. The limits of detection and quantitation were 1.29 and 3.90 ng mL-1, confirming the high sensitivity of the method. Stoichiometric analysis indicated a 2:1 MOX-Zn complex formed through bidentate coordination via carboxylate and carbonyl oxygen atoms. The method was validated in accordance with ICH guidelines, showing satisfactory accuracy, precision, robustness, and reproducibility. It was successfully applied to commercial ophthalmic formulations, yielding results statistically comparable with a reported reference method. The method's environmental sustainability was validated through greenness assessment using both the AGREE metric and GAPI approaches, confirming its favorable ecological profile. The proposed strategy offers a rapid, cost-effective, and eco-conscious alternative to chromatographic techniques for routine pharmaceutical quality control.