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

Significance of the Topic

The legalization of recreational cannabis in Canada has imposed stringent requirements for testing residual pesticides and mycotoxins in dry flower, with reporting limits as low as 20 ppb. Robust, sensitive, and reliable analytical methods are essential to protect consumers and ensure regulatory compliance.

Objectives and Study Overview

This work presents a unified workflow for measuring 96 pesticides and five mycotoxins on the Canadian target list in dry cannabis flower. A single sample preparation strategy feeds both LC/MS/MS and GC/MS/MS platforms, delivering the required sensitivity and reproducibility for federal testing.

Methodology and Sample Preparation

A streamlined extraction uses acetonitrile and vertical shaking with ceramic homogenizers to form a fine powder. Cleanup employs SampliQ C18 EC SPE cartridges to remove cannabinoids, terpenes, and fatty acids. The protocol avoids QuEChERS steps that degrade labile analytes, followed by controlled dilutions (up to 250× for LC and 125× for GC). Matrix-matched calibrators compensate for residual interferences, ensuring accurate quantitation at low ppb levels.

Instrumentation

• LC/MS/MS: Agilent 1290 Infinity II UHPLC coupled to a 6470 or Ultivo triple quadrupole mass spectrometer with JetStream ESI.
• GC/MS/MS: Agilent 7890B GC with multimode inlet and backflush, coupled to a 7010B triple quadrupole featuring an HES source and JetClean in-source cleaning.

Major Results and Discussion

• Recoveries for 88 pesticides and five mycotoxins ranged from approximately 70 % to 110 % with RSDs below 10 %.
• Calibration curves exhibited linearity (R² ≥ 0.99) across target concentration ranges.
• Limits of quantitation in matrix were typically 2.5 ppb for LC/MS/MS and 6.25–12.5 ppb for GC/MS/MS, meeting or exceeding Health Canada requirements.
• The Ultivo performed on par with the 6470 in sensitivity and robustness.
• GC/MS/MS complemented LC/MS/MS for analytes not amenable to electrospray ionization, such as endosulfan isomers and quintozene.

Benefits and Practical Applications

This multiplatform approach reduces sample-preparation time, lowers cross-contamination risk, and simplifies data processing through unified software. Laboratories can rapidly implement the workflow to comply with Canadian regulations and adapt to evolving international standards.

Future Trends and Opportunities

As regulatory limits tighten and target lists expand, future developments may include automated sample preparation, higher-throughput screening, and broader compound coverage. Integration of advanced data analytics and workflow management will support ongoing method optimization and quality assurance.

Conclusion

The described method offers a sensitive, robust, and flexible solution for quantifying residual pesticides and mycotoxins in dry cannabis flower. By combining unified sample preparation with LC/MS/MS and GC/MS/MS analysis, laboratories can meet current and future regulatory demands efficiently.

References

1. Government of Canada. Pest Control Products Act (S.C. 2002, c. 28).
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5. Agilent Technologies. Application Note 5991-9030EN.