A Sensitive and Robust Workflow to Measure Residual Pesticides and Mycotoxins from the Canadian Target List in Dry Cannabis Flower

Significance of the Topic

Legalization of recreational cannabis in Canada has driven the need for stringent safety testing. Health Canada mandates analysis of 96 pesticides and five mycotoxins in dry cannabis flower at reporting limits down to 20 ppb. This represents one of the most comprehensive and challenging residue testing regimes in North America, requiring both liquid chromatography and gas chromatography tandem mass spectrometry to cover diverse analyte chemistries and achieve required sensitivity.

Objectives and Study Overview

The study aimed to develop and validate a sensitive, robust, and unified workflow for quantifying the full Canadian target list of pesticide residues and mycotoxins in dry cannabis flower. Key goals included:

• Achieving reporting limits set by Health Canada
• Minimizing sample preparation complexity and turnaround time
• Ensuring high throughput and instrument uptime
• Providing a flexible platform to adapt to evolving regulations

Methodology and Instrumentation

Sample preparation combined a single-step acetonitrile extraction with dispersive SPE cleanup using a SampliQ C18 EC cartridge. One-gram aliquots of ground cannabis powder were extracted, gravity-eluted through SPE, and aliquots were diluted 25× for LC/MS/MS and 125× for GC/MS/MS to minimize matrix effects. Analysis platforms included:

• Agilent 1290 Infinity II UHPLC coupled to either the 6470 or Ultivo triple quadrupole MS with JetStream ESI source, operated in dynamic MRM mode
• Agilent 7890B GC with a multimode inlet and Purged Ultimate Union backflush, coupled to the 7010B triple quadrupole MS with HES ion source and EI ionization

Key Results and Discussion

Recoveries of 96 pesticides and five mycotoxins met acceptance criteria (typically 70–110 %), with relative standard deviations below 10 % in most cases. Linear calibration (R2 > 0.99) was observed over the required concentration ranges. Limits of quantitation in matrix were as low as:

• 0.01–2.5 ppb for LC/MS/MS
• 5–125 ppb for GC/MS/MS

The Ultivo system matched the sensitivity of the 6470 for low-level pesticides, demonstrating that a compact, next-generation MS can support rigorous compliance testing. GC/MS/MS complemented LC/MS/MS by quantifying nonpolar and thermally stable analytes that are challenging by LC, such as cyclic organochlorines.

Benefits and Practical Applications

The multiplatform approach provides:

• High confidence in compliance by covering all required analytes
• Rapid return on investment through streamlined sample prep and minimized maintenance
• Stable performance and high throughput for routine testing labs
• Adaptability to future expansions of target lists and lower action limits

Future Trends and Opportunities

Ongoing developments in cannabis regulations will likely tighten reporting limits and expand analyte lists. Opportunities include:

• Further automation of sample preparation
• Integration of high-resolution mass spectrometry for non-target screening
• Miniaturized and portable MS solutions for field testing
• Extended workflows for diverse cannabis matrices such as oils and edibles

Conclusion

A robust workflow combining acetonitrile extraction, C18 EC SPE cleanup, and dual LC/MS/MS and GC/MS/MS analysis meets the stringent requirements of Canadian cannabis pesticide and mycotoxin testing. The method delivers high sensitivity, excellent reproducibility, and flexibility to address current and future compliance challenges.

References

• Government of Canada. Pest Control Products Act, S.C. 2002, c. 28.
• Moulins, J. R.; et al. J. AOAC Int. 2018, 101, 1–10.
• Kowalski, J.; et al. LC-GC North Am. 2017, 35, 8–22.
• Turner, C. E.; Elsohly, M. A.; Boeren, T. J. Nat. Prod. 1980, 43, 169–234.
• Agilent Technologies. A Novel Comprehensive Strategy for Residual Pesticide Analysis in Cannabis Flower. Application Note 5991-9030EN, 2019.