Volumetric absorptive microsampling and conductive vial electromembrane extraction for the analysis of pharmaceuticals in whole blood

Volumetric absorptive microsampling (VAMS) enables accurate collection of low blood volumes, independent of hematocrit. Electromembrane extraction (EME) is a sustainable sample clean-up technique; however, its wider applicability to extract analytes directly from VAMS tips remains unexplored. This study aimed to evaluate applicability of the first commercially available conductive vial EME device (with 2-nitrophenyl octyl ether as liquid membrane) for isolating 41 basic pharmaceuticals (log P 2-6) from 10 μL of blood on VAMS tips. The following extraction parameters were optimized: donor solution composition and volume, conductive vials size, applied voltage, extraction time and agitation speed. It was found that: 1/large conductive vials (600 μL) and 300 μL of donor solution provide higher process efficiency and reproducibility compared to smaller vials (200 μL) or larger donor solution volumes; 2/methanol in donor solution improve reproducibility and 3/sonication of VAMS tips in donor solution within a conductive vial prior to extraction enhances process efficiency. The EME protocol, followed by UHPLC-MS/MS analysis, was evaluated for process efficiency, linearity (1-1000 ng/mL), precision, and accuracy. Eleven analytes met most of the predefined acceptance criteria: process efficiencies 34.9-65.8 %, linearity (R²) 0.9933-0.9995, accuracy 85.9-111.1 % and precision 1.4-13.3 % RSD. The extraction was not impacted by hematocrit variation. EME demonstrated superior reproducibility and reduced matrix effects when compared to conventional VAMS tips treatment. This study confirms the reliability of a commercial conductive vial EME device for isolating basic pharmaceuticals from whole blood on VAMS tips, highlighting its potential for routine bioanalytical applications.