Elimination of matrix effects in urine for determination of ethyl glucuronide by liquid chromatography-tandem mass spectrometry.

RATIONALE: Alcohol use disorder affects 4% to 5% of the world's population. Analysis methods are available for various biological fluids to detect this disorder. Determination of ethyl glucuronide in urine by the liquid chromatography-tandem mass spectrometry (LC/MS/MS) method is frequently used in forensic toxicology. These analyses are known to cause matrix effects.

METHODS: The presented study describes the elimination of matrix effects for ethyl glucuronide. This study used two different LC/MS/MS systems containing orthogonal and z-spray ion sources. Ethyl glucuronide was analyzed in negative polarity in electrospray ionization. A different dilution method was chosen for each study. The methods were developed and validated according to the European Medicines Agency bioanalytical method validation parameters.

RESULTS: The lower limit of quantitation of the developed methods was 0.025 μg/mL for ethyl glucuronide. The calibration curve of ethyl glucuronide was between 0.025 and 100 μg/mL with a correlation coefficient of >0.99 for the two methods.

CONCLUSIONS: It was determined that the analyses using the z-spray ion source were more affected by the matrix effect. The two validated methods involve rapid analysis time and simple sample preparation. Also, the methods were applied to real patients' urine.