Direct analysis of ethylene glycol in human serum on the basis of analyte adduct formation and liquid chromatography-tandem mass spectrometry

The aim of this work was to develop a fast, cost-effective and time-saving liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method for the analysis of ethylene glycol (EG) in human serum. For these purposes, the formation/fragmentation of an EG adduct ion with sodium and sodium acetate was applied in the positive electrospray mode for signal detection. Adduct identification was performed with appropriate infusion experiments based on analyte solutions prepared in different concentrations. Corresponding analyte adduct ions and adduct ion fragments could be identified both for EG and the deuterated internal standard (EG-D4). Protein precipitation was used as sample preparation. The analysis of the supernatant was performed with a Luna 5 μm C18 (2) 100 A, 150 mm × 2 mm analytical column and a mobile phase consisting of 95% A (H2O/methanol = 95/5, v/v) and 5% B (H2O/methanol = 3/97, v/v), both with 10 mmol L−1 ammonium acetate and 0.1% acetic acid. Method linearity was examined in the range of 100-4000 μg/mL and the calculated limit of detection/quantification was 35/98 μg/mL. However, on the basis of the signal to noise ratio, quantification was recommended at a limit of 300 μg/mL. Additionally, the examined precision, accuracy, stability, selectivity and matrix effect demonstrated that the method is a practicable alternative for EG quantification in human serum. In comparison to other methods based on liquid chromatography, the strategy presented made for the first time the EG analysis without analyte derivatisation possible.