Ethyl glucuronide determination in meconium and hair by hydrophilic interaction liquid chromatography–tandem mass spectrometry

Ethyl glucuronide (EtG) detection in non-conventional matrices, such as hair and meconium, can provide useful information on alcohol abuse over a long time frame, for example during pregnancy or after a withdrawal treatment. This study reports on the development, validation and application of a new hydrophilic interaction liquid chromatography–tandem mass spectrometry (HILIC–MS/MS) method for the analysis of EtG in meconium and hair. For each matrix, the sample preparation and the chromatographic separation were thoroughly optimised. Additionally, experiments with reversed-phase liquid chromatography were also performed in the development stages. Analyses were carried out using a Phenomenex Luna HILIC column (150mm×3mm, 5μm) and a mobile phase composed by ammonium acetate 2mM and acetonitrile, in gradient. Different SPE cartridges (Oasis MAX, Oasis WAX, aminopropyl silica) and solvents were tested in order to obtain the highest recoveries and cleanest extracts. Optimal results were obtained for meconium with aminopropyl cartridges, while for hair an incubation of 16h with 2mL of water and acetonitrile (50/50, v/v) provided good results. The analytical method was validated for both matrices (meconium and hair) by assessing linearity, precision, accuracy, recovery and limit of quantification. The calibration curve concentrations ranged from 50 to 1200pg/mg for meconium and from 20 to 1000pg/mg for hair. Real meconium and hair samples were analyzed and results were consistent with literature.