A green and robust LC–MS/MS bioanalytical method for sulopenem etzadroxil and probenecid: Optimization, validation, and pharmacokinetic application

A novel, green, and robust Liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous quantification of sulopenem etzadroxil and probenecid in rat plasma, with application to pharmacokinetic studies. Method development was guided by a Box–Behnken Design and response surface methodology, optimizing key chromatographic variables—ethanol proportion (40–60 %), flow rate (0.8–1.2 mL/min), and mobile phase pH (2.8–3.2)—to achieve maximum resolution, peak area, and analytical reproducibility. Chromatographic separation was performed on a Kromasil C18 column using ethanol and 0.1 % TFA (50:50, v/v) as the mobile phase. Mass spectrometric detection employed selected reaction monitoring in positive ion mode using an LC-MS/MS instrument. The method exhibited excellent linearity (10–400 ng/mL), low limits of detection (LOD: ∼3 ng/mL), and quantification (LOQ: ∼9 ng/mL) for both analytes, with recovery rates > 93 % and %CVs < 15 %. Greenness and sustainability assessments using analytical GREEnness metric (AGREE), analytical GREEnness metric for sample PREParation (AGREEprep), complementary green analytical procedure index (ComplexGAPI), Eco-Scale, and Blue applicability grade index (BAGI) confirmed the method’s environmental compatibility and analytical reliability, with scores exceeding 65 across all tools. This validated method demonstrates high sensitivity, reproducibility, and environmental responsibility, rendering it suitable for routine bioanalytical and pharmacokinetic applications.