Analysis of ethyl glucuronide and ethyl sulfate in urine with TSQ Quantis MS

Significance of the Topic

Monitoring ethyl glucuronide (EtG) and ethyl sulfate (EtS) in urine is critical for forensic and clinical toxicology because these minor ethanol metabolites have longer detection windows than ethanol itself. Their reliable quantitation enables retrospective assessment of alcohol consumption, supporting legal, occupational and medical investigations.

Study Objectives and Overview

This work aimed to establish a rapid, sensitive and robust liquid chromatography–tandem mass spectrometry (LC-MS/MS) method on a triple quadrupole instrument for quantitative determination of EtG and EtS in human urine. Key performance metrics included limits of quantitation, assay precision, accuracy and absence of matrix interferences.

Methodology

Sample Preparation:

• Urine samples (50 µL) were mixed with deuterated internal standards (EtG-d5 at 5000 ng/mL; EtS-d5 at 500 ng/mL).
• After 20-fold dilution with water, 5 µL injections were analyzed directly.

Instrumentation

The analysis employed:

• Thermo Scientific Vanquish Flex HPLC with a Phenomenex Synergi Hydro RP column (100 × 3 mm, 2.5 µm).
• Binary mobile phase: 0.1% formic acid in water (A) and methanol (B); 6-minute gradient.
• Thermo Scientific TSQ Quantis triple quadrupole MS with heated electrospray ionization in negative mode.
• Timed selected reaction monitoring (t-SRM) with two transitions per analyte for ion ratio confirmation.

Main Results and Discussion

Limits of Quantitation:

• EtG: 100 ng/mL in authentic urine.
• EtS: 10 ng/mL in authentic urine.

Precision and Accuracy:

• EtG intra-assay precision < 9.8% RSD.
• EtS intra-assay precision < 4.0% RSD.

Matrix Effects:

• No significant suppression or enhancement observed across 17 urine lots; internal standard responses remained within ±20%.

The method produced linear calibration curves and consistent ion ratios at LOQ levels, confirming specificity and reliability.

Benefits and Practical Applications

This workflow offers best-in-class sensitivity and throughput for routine forensic laboratories. Rapid sample preparation and short run times support high sample throughput for compliance testing, clinical research and workplace screening.

Future Trends and Potential Applications

Emerging applications may include integration with high-resolution MS for untargeted metabolite profiling, miniaturized sample prep techniques for microsampling, and adaptation to dried urine spots. Automated data processing platforms and multiplex assays could further streamline toxicological screening panels.

Conclusion

The developed LC-MS/MS method on the TSQ Quantis platform delivers robust, sensitive and reproducible quantitation of EtG and EtS in urine. With low LOQs and minimal matrix interference, it is ideally suited for forensic and clinical alcohol biomarker analysis.