Optimizing Sample Preparation in Pesticides Analysis for Cannabis

Significance of Topic

Cannabis analysis for pesticide residues presents unique challenges due to the plant’s complex matrix rich in terpenes, cannabinoids and other interferences. Regulatory bodies in multiple U.S. states require both LC/MS/MS and GC/MS/MS to ensure consumer safety, and evolving legislation demands ever-lower detection limits. Optimizing sample preparation is critical to achieving reliable quantitation and high laboratory productivity.

Objectives and Study Overview

This study aims to establish a unified sample preparation workflow compatible with both LC-amenable and GC-amenable pesticides and mycotoxins in dried cannabis flower. The approach targets compliance with state-mandated safety action levels, focusing on reducing matrix interferences, improving detection limits and streamlining analysis across platforms.

Methodology and Instrumentation

The sample preparation protocol involves:

• Homogenizing 1 g dried cannabis with ceramic beads or stainless-steel beads using a high-speed shaker.
• Extracting with 15 mL of pesticide-grade acetonitrile.
• C18 solid-phase extraction cleanup (6 mL, 500 mg cartridges).
• Automated dilution: 25-fold for initial extract, followed by platform-specific dilutions (250-fold for LC/MS/MS, 125-fold for GC/MS/MS).

Instrumentation:

• LC/MS/MS: Agilent 1290 Infinity II coupled to either 6470 or Ultivo triple quadrupole MS with Jet Stream ESI source.
• GC/MS/MS: Agilent 8890 GC system with 7010B triple quadrupole MS.

Main Results and Discussion

LC/MS/MS analysis achieved limits of detection between 0.5 and 50 ppb for most pesticides and mycotoxins, meeting at least half of California’s action limits; malathion reached 100 ppb LOD. GC/MS/MS analysis of 43 pesticides delivered limits of quantitation below 0.8 ppb in vial (equivalent to 100 ppb in plant material). Repeatability at LOQ levels showed relative standard deviations under 20 % for key compounds such as pentachloronitrobenzene, captan and chlordane isomers.

Benefits and Practical Applications

• Unified workflow reduces method development time and training requirements.
• High-throughput cleanup and dilution steps minimize matrix effects and instrument maintenance.
• Meets current regulatory thresholds with flexibility to adapt to tighter future limits.

Future Trends and Applications

As regulatory demands expand to include additional pesticides and enforce lower detection limits, laboratories may integrate automation, high-resolution mass spectrometry and multi-residue methods. Advanced data processing and automated SPE platforms will further enhance throughput and consistency.

Conclusion

The optimized, multiplatform sample preparation protocol delivers robust, sensitive and reproducible pesticide and mycotoxin analysis in dried cannabis flower. Aligned with Agilent’s instrumentation, it ensures regulatory compliance and laboratory efficiency now and in the future.

References

1. Roy J-F, et al. A Sensitive and Robust Workflow to Measure Residual Pesticides and Mycotoxins from the Canadian Target List in Dry Cannabis Flower, Agilent Technologies Application Note, 5994-0429EN, 2018.
2. Andrianova A, Westland J, Churley M. Sensitive and Robust Detection of Pesticides Regulated in California in Dried Cannabis Plant Material, Agilent Application Note, 5994-0568EN, 2019.
3. Stone PJW, et al. Determination of Pesticides and Mycotoxins as Defined by California State Recreational Cannabis Regulations - A Combined LC/MS/MS Analysis Method, Agilent Application Note, 5994-0648EN, 2019.