A rapid GC-MS method for the simultaneous determination of bupropion and hydroxybupropion in plasma using SALLME and microwave-assisted derivatization.

Bupropion is widely used in the treatment of major depressive disorder and smoking cessation, and its clinical response is largely influenced by its active metabolite, hydroxybupropion. Due to significant pharmacokinetic variability and the therapeutic relevance of hydroxybupropion concentrations, reliable analytical methods suitable for therapeutic drug monitoring (TDM) are required. In this study, a rapid gas chromatography-mass spectrometry (GC-MS) method was developed for the simultaneous determination of bupropion and hydroxybupropion in human plasma using a novel sample preparation strategy termed KUL-SPEED (Kul's Ultra-fast, Low-step Sample Preparation with Efficient Extraction and Derivatization). The method integrates salt-assisted liquid-liquid microextraction (SALLME) with microwave-assisted trimethylsilylation in a unified workflow, eliminating solvent evaporation and reconstitution steps. Sample preparation and derivatization were completed within approximately 5 min, and chromatographic separation was achieved within an 8-minute total run time. Method validation was performed according to ICH M10 guidelines. Calibration was linear over 50-2000 ng/mL for bupropion and 250-2000 ng/mL for hydroxybupropion, with acceptable accuracy, precision, stability, and matrix effect results. The method was successfully applied to patient plasma samples, confirming its applicability for routine TDM. The KUL-SPEED approach may also be adaptable to other derivatizable analytes in biological matrices.