A novel sensitive and validated spectrofluorimetric framework for betrixaban determination in different matrices using erythrosine B–based fluorescence quenching

Abstract A novel, sensitive, and eco-friendly spectrofluorimetric approach was developed for quantifying betrixaban. This technique is based on quenching the intrinsic fluorescence of erythrosine B in an acidic Toerell–Stenhagen buffer (pH 4.0). Stern-Volmer analysis confirmed the formation of a non-fluorescent ion-pair complex, revealing static quenching with high bimolecular quenching rates. The fluorescence quenching (measured at λex = 528 nm and λem = 556 nm) displayed excellent linearity across a broad concentration range of 10.0–10,000 ng/mL ( r = 0.9999). Validated per ICH Q2R2 guidelines, the method exhibited limits of detection and quantification of 2.97 ng/mL and 8.99 ng/mL, respectively, with an outstanding mean recovery of 100.50% ± 0.97. Robustness was verified against minor variations in pH, buffer volume, and reaction time. Practical applicability was proven by successfully analyzing betrixaban in pharmaceutical capsules and spiked human plasma. Statistical comparison with a reported spectrophotometric method showed no significant difference in accuracy and precision, establishing this economical and highly sensitive method for routine quality control and pharmacokinetic studies. Furthermore, the method’s environmental sustainability was confirmed using GAPI, AGREE, SAMI, BAGI and EVG tools, validating its superior greenness profile and adherence to green analytical chemistry principles.