Routine Analysis of Cannabis for Pesticides and Mycotoxins using UPLC-MS/MS and GC-MS/MS

Importance of the Topic

The rapid growth of legal cannabis markets for medicinal and recreational use has created a strong demand for reliable safety testing. Pesticide residues and fungal toxins in cannabis flower can pose health risks to consumers. Developing a streamlined, high-throughput method to detect hundreds of pesticide active ingredients alongside major mycotoxins addresses both regulatory requirements and public health concerns.

Objectives and Overview of the Study

This study aimed to establish a single-injection workflow combining liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) and gas chromatography–tandem mass spectrometry (GC-MS/MS) for the simultaneous quantitation of multi-class pesticides and key mycotoxins in cannabis flower. The method was designed to meet California action levels for residues and to streamline sample preparation and data processing.

Methodology and Instrumentation

Sample Preparation and Cleanup:

• Weigh 0.5 g of ground cannabis flower into a centrifuge tube.
• Add 5 mL acetonitrile and homogenize using a Geno Grinder (5 min at 1500 rpm).
• Withdraw 1 mL extract for dispersive SPE cleanup (shake 1 min, centrifuge).
• Transfer supernatant to autosampler vials.

Chromatographic and Mass Spectrometric Conditions:

• UPLC-MS/MS: Waters Acquity H-Class with Xevo TQ-S micro; XBridge C18 column (2.1 × 150 mm, 2.5 µm); water + 5 mM ammonium formate/0.02% formic acid (A) and methanol (B); flow 0.4 mL/min; injection 5 µL.
• GC-MS/MS: Waters Xevo TQ-GC; Rxi-5MS column (20 m × 0.18 mm × 0.18 µm); helium carrier gas; oven ramp from 60 °C to 330 °C; injection 1 µL at 280 °C.
• Quanpedia Method Database: automated generation of LC, GC, MS acquisition and processing methods, with rapid retention time adjustment for MRM transitions.

Main Results and Discussion

Analytical Performance:

• Recoveries for most pesticides and mycotoxins ranged between 80 % and 120 %.
• Matrix suppression was significantly reduced by dSPE cleanup.
• Linearity: R² > 0.990 over 0.025–0.50 µg/g for pesticides and R² > 0.990 over 0.005–0.10 µg/g for mycotoxins.
• Representative MRM chromatograms confirmed baseline‐resolved detection of key analytes including mevinphos isomers, dimethomorph, fenhexamid, coumaphos, spinetoram, chlorpyriphos, aflatoxins B1, B2, G1, G2 and ochratoxin A.

The combination of UPLC-MS/MS for most pesticides and mycotoxins with GC-MS/MS for poorly ionizing chlorinated compounds (e.g., chlordane isomers, captan degradant THPI, PCNB) provided robust confirmatory data.

Benefits and Practical Applications of the Method

• High throughput: streamlined sample cleanup and single-injection dual analysis.
• Regulatory compliance: meets California action levels for over 200 pesticide residues and five mycotoxins.
• Enhanced data quality: reduced matrix effects and improved sensitivity at low ppb levels.
• Automation support: Quanpedia database simplifies method development and minimizes manual errors.

Future Trends and Applications

Expanding the method’s scope may include:

• Integration of high-resolution MS for non-targeted screening of emerging contaminants.
• Miniaturized or on-line sample preparation to further increase throughput.
• Machine learning algorithms for automated peak detection and quantitation.
• Broader multi-matrix application to edibles, concentrates, and hemp products.

Conclusion

The described workflow combining UPLC-MS/MS and GC-MS/MS with a simple acetonitrile extraction and dSPE cleanup offers a fast, sensitive, and versatile platform for routine cannabis safety testing. It effectively meets regulatory criteria for pesticide residues and mycotoxins while reducing matrix interferences and simplifying data processing.

References

1. Tran K., Organtini K., Twohig M., Alden P., Young M.S., Meruva N., Rosnack K., Fujimoto G., Stevens R., Roush J., Hudalla C.J. Analysis of Residual Pesticides and Mycotoxins in Cannabis Using UPLC-MS/MS and GC-MS/MS to Meet California Regulatory Requirements. Waters Application Note 720006465EN.