Analysis of capivasertib via ion-pairing with erythrocin B as a spectrofluorometric probe

Abstract A novel, eco-friendly spectrofluorimetric method has been developed for the sensitive determination of capivasertib, based on resonance Rayleigh scattering enhancement. Unlike previously reported methods, this approach utilizes erythrosine B as a safer ion-pairing reagent in an acidic aqueous medium, eliminating the need for organic solvents or complex extraction steps. The interaction between capivasertib and erythrosine B leads to a stable ion-pair complex, producing a strong Rayleigh scattering signal measurable at λex530/λem550 nm. The method demonstrated excellent linearity over the range of 20–2000 ng mL⁻¹, with a detection limit of 5.61 ng mL⁻¹ and a quantification limit of 17 ng mL⁻¹. All analytical parameters were optimized and validated according to ICH guidelines. To holistically substantiate sustainability, the method’s environmental and practical profiles were appraised using all contemporary greenness/whiteness/applicability metrics employed in this work: Analytical Eco-Scale (ESA), NEMI pictogram, GAPI, AGREE, and AGREE-prep for sample-preparation greenness; the White Analytical Chemistry RGB12 model (whiteness); and the Blue Applicability Grade Index (BAGI) (blueness/applicability). This work introduces a greener, simpler, and more accessible alternative for capivasertib analysis, with potential applications in pharmaceutical quality control and routine laboratory testing.