Ultrafast Screen for Synthetic Cannabinoids in Urine Using the Agilent RapidFire High-Throughput Mass Spectrometry System

Significance of the Topic

Synthetic cannabinoids represent a rapidly evolving class of designer drugs often encountered in forensic and clinical toxicology. Their structural diversity and continual modification challenge traditional screening methods. High-throughput, selective assays are essential for timely and accurate detection in biological matrices such as urine. The Agilent RapidFire high-throughput mass spectrometry system addresses the growing demand for speed and analytical capacity in forensic drug screening laboratories.

Objectives and Study Overview

This study aimed to develop and evaluate an ultrafast online solid-phase extraction with tandem mass spectrometry (SPE/MS/MS) method on the Agilent RapidFire platform for the detection of seven synthetic cannabinoid metabolites in urine. Key objectives included:

• Assessing the sample cycle time and throughput.
• Establishing linearity, precision, and accuracy across a broad concentration range (5–1000 ng/mL).
• Comparing analytical performance to conventional GC/MS and LC/MS assays.

Methodology and Sample Preparation

Drug-free human urine was spiked with metabolites of JWH-018, JWH-073, JWH-081, JWH-210, JWH-250, RCS-4, and AM2201. Samples underwent base hydrolysis at 65 °C, followed by tenfold dilution with 50:50 methanol/water containing 0.1% formic acid. Ten microliters of prepared sample were injected into the RapidFire SPE system using a reversed-phase C4 cartridge. A gradient of aqueous ammonium acetate/formic acid and organic solvents (methanol, ethyl acetate/isopropanol) facilitated rapid analyte extraction and elution. Mass spectrometric detection employed multiple reaction monitoring transitions optimized for each analyte and a deuterated internal standard. Detailed MS parameters included a gas temperature of 250 °C, 19 L/min gas flow, 300 °C sheath gas temperature, and capillary voltage of 3 500 V.

Used Instrumentation

• Agilent RapidFire 360 high-throughput sampling system
• Agilent 6490 Triple Quadrupole Mass Spectrometer
• Agilent MassHunter Qualitative Analysis B.05.00
• Agilent MassHunter Quantitative Analysis B.05.00
• Agilent RapidFire C4 SPE cartridge (G9210C)

Key Results and Discussion

The method achieved a cycle time of 12 seconds per sample, equating to over 250 injections per hour. Calibration curves for all analytes displayed excellent linearity (R2 > 0.9998) across 5–1000 ng/mL. Intraday and interday accuracy values were within ±15% and precision (CV) below 10% for all concentrations. Reproducibility testing over 2000 sequential injections showed stable pump performance, consistent peak shape, and no cartridge degradation. Representative results for JWH-073 N-butanoic acid demonstrated linear response, high sensitivity, and stable signal intensity throughout extended runs.

Benefits and Practical Applications

The ultrafast SPE/MS/MS workflow offers:

• Rapid turnaround and high throughput for forensic and clinical laboratories.
• High selectivity and sensitivity without extensive sample preparation.
• Flexibility to expand or modify the analyte panel as new synthetic cannabinoids emerge.
• Reduced solvent consumption and instrument idle time compared to LC/MS methods.

Future Trends and Applications

Advances in high-throughput mass spectrometry are expected to integrate automated sample handling, data processing, and broader metabolite libraries. Emerging trends include coupling ultrafast SPE/MS/MS with machine learning algorithms for pattern recognition and real-time reporting. The method can be adapted to additional drug classes and alternative biological matrices, supporting rapid response to evolving drug threats.

Conclusion

The Agilent RapidFire high-throughput SPE/MS/MS approach provides a robust, rapid, and precise solution for synthetic cannabinoid screening in urine. It meets the increasing demands of forensic toxicology for speed, flexibility, and analytical performance, outperforming traditional GC/MS and LC/MS assays in throughput and operational efficiency.