Quantitative LC/MS/MS Analysis of Ethyl Glucuronide and Ethyl Sulfate Using a Charged Surface-C18 Column

Significance of the Topic

Monitoring nonvolatile metabolites of ethanol, such as ethyl glucuronide (EtG) and ethyl sulfate (EtS), provides a reliable indicator of recent alcohol consumption. Their detection in biological fluids supports clinical diagnostics, forensic investigations, workplace testing, and compliance monitoring.

Objectives and Study Overview

This study aimed to develop and validate a rapid, robust LC–MS/MS method for quantifying EtG and EtS in urine. Key goals included achieving high sensitivity, reproducibility, and linearity across a wide concentration range while minimizing sample preparation steps.

Methodology

Sample Preparation:

• Urine specimens diluted 1:50 with 0.01% formic acid in water.
• Internal standards (EtG-d5, EtS-d5) spiked to yield 500 ng/mL and 50 ng/mL in final solutions.
• Simple “dilute and shoot” workflow in vials.

Chromatographic Conditions:

• Column: Agilent InfinityLab Poroshell 120 CS-C18 (2.1 × 50 mm, 2.7 µm).
• Mobile phase A: 0.01% formic acid in water; B: methanol.
• Gradient: 2% B initial, ramped to 98% B at 3 min, total run 4 min, flow 0.35 mL/min.
• Column temperature: 40 °C; injection volume optimized at 2 µL.

Instrumentation

• Agilent 1290 Infinity II LC system (binary pump, multisampler at 4 °C, column compartment).
• Agilent 6470 and Ultivo triple quadrupole MS with Jet Stream ESI in negative mode.
• MassHunter suite for data acquisition and quantitative analysis.

Main Results and Discussion

Linearity and Sensitivity:

• Calibration ranges: EtG 100–10 000 ng/mL, EtS 10–1000 ng/mL.
• Correlation coefficients (R²) exceeded 0.99 for both analytes.

Precision and Stability:

• Reproducible peak areas over 1000 injections (200 replicates per sample), retention time variation remained minimal over 800 injections.
• Optimal sample dilution (1:50) and injection volume (2 µL) balanced signal intensity and peak shape.

Benefits and Practical Applications

This method offers:

• Rapid turnaround (4 min per run) and minimal sample handling.
• High throughput capability for clinical and forensic laboratories.
• Reliable quantitation suitable for routine compliance screening and research studies.

Future Trends and Applications

Emerging opportunities include:

• Integration with automation platforms for unattended processing.
• Extension to additional alcohol biomarkers or complex matrices (e.g., blood, plasma).
• Adoption of high-resolution MS for simultaneous screening of broader metabolite panels.

Conclusion

The developed LC–MS/MS approach utilizing a charged surface C18 column delivers accurate, reproducible quantitation of EtG and EtS in urine with minimal sample prep. Its robustness and speed make it well suited for clinical, forensic, and workplace testing applications.

Reference

Rasmussen N., Szczesniewski A. Quantitative LC/MS/MS Analysis of Ethyl Glucuronide and Ethyl Sulfate Using a Charged Surface-C18 Column. Agilent Technologies, Application Note, April 2022.