Analysis of the Canadian Cannabis Pesticides List Using Both ESI and APCI Techniques

Importance of the Topic

Federal legalization of recreational cannabis in Canada has introduced stringent pesticide residue limits that surpass those of other jurisdictions. Ensuring consumer safety and regulatory compliance requires sensitive and robust analytical methods capable of detecting trace levels of diverse pesticide chemistries in complex cannabis matrices.

Study Objectives and Overview

This study aimed to develop a streamlined liquid chromatography tandem mass spectrometry workflow combining electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) to quantitatively screen the Health Canada pesticide panel in dried cannabis flower. The method targets 96 analytes at maximum residue limits as low as 0.01 µg/g, using a single sample extract.

Methodology and Instrumentation

Sample Preparation:

• Homogenize and extract 1 g dried flower with 10 mL acetonitrile in two sequential steps.
• Winterize extracts at –20 °C and centrifuge to remove co-extractives.
• Dilute supernatant 1:1 with methanol and inject 1 µL for ESI, 4 µL for APCI.

Chromatography and Detection:

• Separation on Phenomenex Luna Omega Polar C18 (150×3 mm, 3 µm) at 420 µL/min and 30 °C.
• SCIEX ExionLC™ AD system with IonDrive™ Turbo V source.
• Detection on SCIEX QTRAP® 6500+ with Scheduled MRM™, using optimized ESI and APCI source parameters.

Key Results and Discussion

The dual-ionization approach achieved or exceeded Health Canada LOQs for all but one compound (kinoprene) in dried cannabis. ESI provided high sensitivity for polar pesticides, while APCI enabled quantitation of non-ionizable and GC-traditionally analyzed analytes. Combined run time per sample was under 30 minutes, and matrix suppression was minimized by solvent extraction and winterization without extensive cleanup.

Benefits and Practical Applications

By covering the full pesticide panel on a single LC-MS/MS platform, this method eliminates laborious derivatization and GC-MS maintenance, reduces analysis costs, and increases laboratory throughput. Its robustness against matrix effects makes it suitable for various cannabis products, including flowers and oils, with potential extension to edibles.

Future Trends and Potential Applications

Emerging directions include integration of lipid removal strategies for oil matrices, expanding analyte ranges (e.g., mycotoxins), higher-volume injection for challenging LOQs, and adopting data analytics for automated processing. Continued evolution of ionization technologies and green sample-prep approaches will further streamline high-throughput testing.

Conclusion

The developed LC-MS/MS workflow utilizing both ESI and APCI confidently meets Health Canada pesticide residue requirements in cannabis. Its streamlined extraction, dual-mode ionization, and rapid analysis offer a robust, flexible solution for regulatory compliance and consumer safety.

References

1. Quantitation of Oregon List of Pesticides and Cannabinoids in Cannabis Matrices by LC-MS/MS. SCIEX 2018.
2. Achieving the California Pesticide Regulations in Cannabis Using Optimized APCI and ESI Techniques. SCIEX 2019.
3. Health Canada. Mandatory Cannabis Testing For Pesticide Active Ingredients – Lists and Limits. 2018.
4. Moulins JR et al. Multiresidue Method of Analysis of Pesticides in Medical Cannabis. J AOAC Int. 2018;101(6):1948-1960.