A validated method for capillary phosphatidylethanol 16:0/18:1 quantification with two different 10-µl volumetric absorptive microsample devices in the same setup.

This article focuses on the development and validation of a volumetric absorptive microsampling (VAMS) method for quantifying phosphatidylethanol (PEth), an alcohol biomarker, in 10 µl capillary blood samples using two devices: Capitainer®B Vanadate and Mitra®. The study adapted an existing ISO 15189-accredited ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS-MS) method for venous blood to analyze dried blood spots collected by these VAMS devices, achieving a measuring range of 0.03 to 4.0 µM (21–2812 ng/mL). Validation results showed that the Mitra device met all accuracy and precision criteria, while Capitainer met all except for accuracy at PEth concentrations ≥0.5 µM, where it slightly underestimated values by about 7.6%. Both devices demonstrated acceptable stability, minimal hematocrit effects after internal standard correction, and good correlation with venous blood results, supporting their suitability for PEth analysis in capillary blood.