Fast Screening for Selected Doping Substances in Urine Samples Using GC-TOFMS

Significance of the Topic

Rapid and comprehensive screening for performance-enhancing and illicit drugs in biological matrices is a cornerstone of anti-doping control, forensic toxicology, and workplace drug testing. Conventional GC-MS approaches rely on selective ion monitoring, necessitating multiple targeted analyses to cover diverse compound classes. The integration of time-of-flight mass spectrometry (TOFMS) with intelligent data deconvolution enables full-scan acquisition at high speeds and sensitivities, offering a streamlined workflow for broad-spectrum drug detection in complex samples such as urine.

Objectives and Study Overview

This work aimed to develop and validate a fast gas chromatography–TOFMS (GC-TOFMS) method coupled with solid-phase extraction (SPE) for simultaneous screening of beta-blockers, amphetamines, opiates, and other doping substances in urine. Key goals included achieving run times under nine minutes, reliable automated identification of coeluting peaks, and detection limits suitable for routine anti-doping applications.

Methodology and Instrumentation

• Sample Preparation: Enzymatic hydrolysis of 2.5 mL urine followed by SPE and elution with chloroform/2-propanol (80:20) containing 2 % ammonia; concentrates were dried and derivatized with MSTFA at 60 °C for 30 min.
• GC Conditions: Agilent 6890 gas chromatograph, XTI-5 capillary column (20 m × 0.18 mm × 0.20 µm), injector at 250 °C, split ratio 5:1, helium at 1.4 mL/min, oven ramp from 150 °C to 320 °C at 30 °C/min (total run <9 min).
• TOFMS Parameters: LECO Pegasus GC-TOFMS, ion source at 170 °C, mass range m/z 60–600, acquisition rate 20 spectra/s, total acquisition time 500 s.

Main Results and Discussion

• A standard mixture of 35 drugs (beta-blockers, amphetamines, opiates) at 2 µg/mL yielded clear separation and high-quality spectra despite rapid GC conditions.
• A targeted subset of 14 analytes was processed via a reference table; all compounds were automatically identified and semi-quantified with signal-to-noise ratios above 100:1 at 0.4 µg/mL in spiked urine.
• Deconvolution algorithms successfully resolved coeluting beta-blockers (pindolol and propranolol) even below the baseline, demonstrating robust peak finding and spectral extraction.
• Across one sample, over 270 compounds with S/N >30 were detected, highlighting the ability to uncover non-targeted substances through library searching of deconvoluted spectra.

Benefits and Practical Applications

• High throughput: sub-9-minute GC runs facilitate large-scale screening in anti-doping and forensic labs.
• Comprehensive coverage: full-scan TOFMS captures a broad range of drug classes without sacrificing sensitivity.
• Automated data processing: deconvolution and library matching streamline analysis of complex biological matrices.

Future Trends and Potential Applications

• Expansion to other drug classes and biomarkers through tailored reference libraries and increased mass range coverage.
• Integration with high-resolution TOFMS and hybrid instruments to improve identification confidence and quantify low-abundance analytes.
• Application of machine learning algorithms for enhanced pattern recognition and non-targeted screening in clinical and environmental monitoring.

Conclusion

The combination of fast GC separation, SPE sample cleanup, and high-speed TOFMS with automated deconvolution offers a powerful platform for rapid, sensitive, and comprehensive drug screening in urine. This approach meets the demands of anti-doping laboratories and forensic toxicology by reducing analysis time, simplifying workflows, and enabling discovery of both targeted and unexpected analytes.