Spectrofluorometric and spectrophotometric assay of anticancer drug ensartinib using ion-pair complex formation reaction with eosin Y

Two simple, sensitive, and eco-friendly spectroscopic methods were developed for the determination of ensartinib through ion-pair complexation with eosin Y. Method A represents the first reported spectrofluorometric assay for the studied drug and it is based on fluorescence quenching of eosin Y at pH 3.3, showing linearity over 100–1000 ng mL⁻¹ with LOD and LOQ values of 21.2 and 64.1 ng mL⁻¹, respectively. Method B is a spectrophotometric method based on measuring the absorbance of the formed ion-pair complex at 550 nm, obeying Beer’s law over 1.0–10.0 µg mL⁻¹, with LOD and LOQ values of 132 and 400 ng mL⁻¹, respectively. Both methods were validated according to ICH guidelines and exhibited excellent accuracy (98.51–101.68%) and precision (RSD < 2%). The proposed procedures were successfully applied to capsules, providing mean recoveries of 99.29 ± 1.11% and 100.39 ± 0.98% for Methods A and B, respectively. Statistical comparison with a reported chromatographic method showed no significant difference at the 95% confidence level. The environmental impact of the developed methods was assessed using AGREE and GAPI tools, confirming their compliance with green analytical chemistry principles.