Development of a Sensitive Fluorimetric Method for Atomoxetine Determination in Tablets and Plasma Using a Dansyl Chloride Derivatization Approach

New, eco-friendly method for analyzing atomoxetine (AXT) was developed using dansyl chloride as a fluorescent derivative. The method demonstrated a linear range from 50.0 to 900.0 ng mL⁻¹ with a detection limit of 15.96 ng mL⁻¹. It exhibited linearity (r² = 0.9995) and detection/quantification limits of 15.96 and 48.38 ng mL⁻¹, respectively. The method demonstrated accuracy recoveries of 99.56% ± 1.11% to 100.67% ± 0.79% and precision ranging from 98.87% ± 1.91% to 102.54% ± 0.51% across 200.0 to 800.0 ng/mL. The proposed method, applied to capsules, spiked plasma, and real human plasma samples, demonstrated excellent accuracy, precision, and overall performance. Validation was performed according to International Conference on Harmonization (ICH) guidelines. The % Recovery ± SD of the proposed and reported methods was similar, with t-values (0.27–0.76) and F-values (1.37–3.17), confirming the method's reliability and consistency. Sustainability profiling using the RGB12 algorithm, Green Certificate, AGREE, SPMS, and BAGI tools showed a good sustainability profile.