Incorporation of Tetrahydrocannabinol into a Mixed Drug Substances Panel – Application to Three Commercially Available Oral Fluid Collection Devices

Importance of the topic

Oral fluid drug testing offers a non-invasive and supervised approach for detecting a range of illicit and prescription compounds at low concentrations. Ensuring a robust and universal sample preparation method that accommodates diverse commercial collection devices is critical for forensic and workplace drug testing laboratories.

Study objectives and overview

The primary goal of this work was to establish a single extraction protocol for a mixed analyte panel—including tetrahydrocannabinol (THC) and 26 other drugs—that can be applied across three leading oral fluid collection systems. The study evaluated the performance of the method with respect to sensitivity, reproducibility, and compliance with European Workplace Drug Testing Society (EWDTS) guidelines.

Methodology and instrumentation

The study employed Waters Oasis MCX 96-well µElution plates for mixed-mode extraction of analytes from limited oral fluid volumes (<75 µL equivalent). Post-elution, samples were split into two aliquots: one reconstituted in 50% acetonitrile for targeted THC analysis and the other in 5% acetonitrile with 0.1% human plasma for the remaining compounds. Dual UPLC-MS/MS methods ran consecutively on the same ACQUITY UPLC BEH C18 column, avoiding column switching. Detection used Xevo TQ-S micro mass spectrometry with MRM transitions for quantifier and qualifier ions, processed by TargetLynx.

Instrumentation used

• Oasis MCX 96-well µElution Plate (P/N 186001830BA)
• ACQUITY UPLC I-Class System with FTN
• ACQUITY UPLC BEH C18 Column (P/N 186002352)
• Xevo TQ-S micro Mass Spectrometer

Main results and discussion

Chromatographic separation allowed confirmation of THC at 2 ng/mL across all collection devices (Immunalysis Quantisal, Sarstedt Salivette, Greiner Bio-One) with consistent peak shape and signal intensity. The remaining 26 analytes were resolved at EWDTS cut-offs (≤2 ng/mL for confirmation) in under 15 minutes. Figures demonstrating MRM chromatograms confirmed adequate sensitivity and specificity. Method precision and recovery met current forensic testing standards.

Benefits and practical applications

• Universal sample prep compatible with multiple commercial devices
• Reduced sample volume requirement (<75 µL neat fluid)
• High throughput potential via automation on 96-well format
• Fast turnaround time (<15 min per run) for mixed drug panels

Future trends and applications

Advancements may include integration with automated liquid handlers for fully unattended workflows, expansion of analyte panels to emerging drugs of abuse, and adaptation to point-of-care testing platforms. Machine learning-driven data processing could further streamline result interpretation.

Conclusion

The study demonstrates a versatile, sensitive, and high-throughput method for simultaneous extraction and analysis of THC alongside a broad panel of drugs in oral fluid. Using a single µElution SPE protocol and dual UPLC-MS/MS methods ensures compliance with international guidelines and simplifies laboratory operations.

References

• European Workplace Drug Testing Society Guidelines. EWDTS; accessed June 29, 2017.
• Danaceau A et al. Direct Analysis of Opioids and Metabolites in Oral Fluid by Mixed-Mode µElution SPE Combined with UPLC-MS/MS for Forensic Toxicology. Waters Application Note 720004838EN; 2013.
• Lee R, Wood M. Using UPLC-MS/MS for the Quantitation of Illicit or Prescription Drugs in Preserved Oral Fluid. Waters Application Note 720005584EN; 2016.