Analysis of the alcohol biomarker phosphatidylethanol by NACE with on‐line ESI‐MS

Abstract

Phosphatidylethanol (Peth), a group of aberrant phospholipids formed in cell membranes in the presence of ethanol, has been recently proposed as biomarker of chronic alcohol abuse. The aim of this study was to develop a new analytical method, based on NACE online coupled with a mass spectrometer for the analysis of Peth in blood. For this purpose an ion-trap mass spectrometer equipped with an orthogonal ESI source operating in negative ion mode was used. An alkaline solution of ammonium acetate 5 mM (pH 9) in water/methanol (MeOH) (80:20 v/v) was delivered as coaxial sheath liquid. All experiments were performed using an uncoated fused-silica capillary (90 cm x 75 microm id). The effects of variable percentages of ACN, MeOH, 2-propanol, dichloromethane, along with variable concentrations of ammonium acetate were investigated for the separation of Peth. Collectively, a separation medium composed of ACN (45% v/v), 2-propanol (20% v/v), dichloromethane (20% v/v), MeOH (10% v/v), water (5% v/v), and ammonium acetate (25 mM) was chosen. The estimated LOD was 0.1 microM, while LOQ was 0.4 microM. Within-run (intra-day) and between-run (inter-day) precision was always lower than 15%. The method proved to be robust and reliable. The MS detector allowed the simultaneous identification of several Peth homologues, and the use of an internal standard (phosphatidylbutanol) with similar electrophoretic properties of that of Peth increased quantitation effectiveness.

Phosphatidylethanol in Blood as a Marker of Chronic Alcohol Use: A Systematic Review and Meta-Analysis

“…The two electrophoretic methods based on non-aqueous capillary electrophoresis, either coupled to an UV [64] or to a mass spectrometric detector [65] have also found very limited clinical application.…”

Determination of maternal-fetal biomarkers of prenatal exposure to ethanol: A review

“…Several analytical approaches have been utilized so far for quantifying PEth in blood and other biological matrices and tissues: TLC [129], LC coupled to ESI - [132,133] or TOF -MS [134], LC coupled to an evaporative light-scattering detector (ELSD) [130,132,135], non-aqueous capillary electrophoresis (NACE) with conventional UV detection [136] and NACE system coupled with an online ESI-MS [137]. The last mentioned method has proved to be sensitive and accurate, currently being the most utilized one.…”

CE-MS in Forensic Sciences with Focus on Forensic Toxicology

“…A NACE-ESI-ion trap MS method for the detection and quantitation of PEth in blood was developed and validated by Nalesso et al [116]. Indeed, the poor solubility of PEth in aqueous media made NACE the electrophoretic technique of choice for the separation of this compound.…”