Background: Detection of alcohol consumption after a longer period can be useful in certain patient groups. To monitor chronic alcohol consumption, a novel analytical method for the quantification of phosphatidylethanols (PEths) was developed and validated using ultra performance convergence chromatography-Tandem mass spectrometry. Methods: The main phosphatidylethanols like palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanol (POPEth), 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphoethanol, and 1,2-dioleoyl-sn-glycero-3-phosphoethanol were analyzed using a simple and fast sample preparation protocol followed by chromatographic separation using ultra performance convergence chromatography, a novel kind of supercritical fluid chromatography. Mass spectrometric detection was conducted by applying negative electrospray ionization and multiple reaction monitoring mode. Only 50 L of whole blood is needed for the simultaneous quantification of all 3 compounds within 5-minute run-To-run analysis time. POPEth-d5 was applied as internal standard. Results: The method was validated according to the Food and Drug Administration guidelines. Correlation coefficients were higher than 0.995 for all 3 compounds. Intraday and interday inaccuracies were <15% for all analytes in the established linear range. Intraday and interday imprecision were <15% for all analytes. Lower limit of quantification for 1,2-dioleoyl-sn-glycero-3-phosphoethanol, palmitoyl-2-linoleoyl-sn-glycero-3-phosphoethanol, and POPEth are, respectively, 3, 6, and 6 mcg/L. Sample stability at-80°C was 1 year. Extracts were stable for 1 day in the autosampler and 2 days at 2-8°C in a closed Eppendorf tube. Samples were tested after 3 freeze-Thaw cycles and considered stable. Patient samples have been analyzed with this new method. In a cohort of 248 pregnant women, 17 patients (6.9%) scored positive for PEth. Conclusions: The described method is suitable for the simultaneous quantitative analysis of the most abundant PEth homologues. Major advantages are low LLOQs, minimal sample volume and clean-up, and a short run time. The method is now available to monitor alcohol consumption in patients and has been incorporated in clinical practice and research.

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Therapeutic Drug Monitoring
Erasmus MC: University Medical Center Rotterdam

van der Nagel, B., Wassenaar, S., Bahmany, S., & Koch, B. (2018). Quantification of Phosphatidylethanols in Whole Blood as a Proxy for Chronic Alcohol Consumption, Using Ultra Performance Convergence Chromatography Tandem Mass Spectrometry. Therapeutic Drug Monitoring, 40(2), 268–275. doi:10.1097/FTD.0000000000000492