A validated method for the separation of ethyl glucoside isomers by gas chromatography-tandem mass spectrometry and quantitation in human whole blood and urine.

Ethyl glucoside (EG) is present in Japanese sake in high concentrations, and can be found in other alcoholic beverages like beer and wine in varying amounts. EG exists as alpha (α) and beta (β) isomers, and the concentrations and ratios of these isomers differ depending on the alcoholic beverage. Herein, we report a validated analysis method for the separation of EG isomers in human whole blood and urine, by GC-MS/MS. Whole blood and urine samples were deproteinized and interferences removed by weak cation exchange cartridges. The target analytes were acetylated using acetic anhydride and pyridine by microwave-accelerated derivatization. Separation was performed using tandem columns, with detection in the multiple reaction monitoring (MRM) mode. The MRM transitions for all compounds were m/z 157.0 > 115.1 for the quantifying transition, and m/z 157.0 > 73.1 and m/z 141.0 > 81.0 for the qualifying transitions. Assay validation included linearity, LOD and LLOQ, bias, within-run and between-run precision, stability, and dilution integrity. Baseline separation of the 2 isomers was achieved with linear calibration (r > 0.99) across the calibration range 0.625 to 50 μg/mL for both α- and β-EG in both whole blood and urine. The validated method was then applied to actual human whole blood and urine samples collected at autopsy, as well as relevant alcoholic beverage samples. The quantitation of EG isomers could benefit the forensic toxicology community by acting as markers for recent alcoholic beverage consumption.