Determination of the Oregon Pesticide List in Cannabis Using a Simple Extraction Procedure With dSPE Cleanup and UPLC-MS/MS

Significance of the Topic

With growing legal acceptance of medical and recreational cannabis, ensuring the safety of cannabis products is critical. Pesticide residues can pose health risks, and state regulations define strict action limits. Developing rapid and robust analytical methods to screen a broad range of pesticides in complex cannabis matrices supports quality control and regulatory compliance.

Study Objectives and Overview

This study aimed to implement a simple extraction and dispersive solid phase extraction cleanup workflow followed by UPLC-MS/MS to simultaneously analyze the 59 pesticides regulated by the Oregon Cannabis Pesticide Guide List. The approach leverages preconfigured methods from the Quanpedia Database to reduce method development time.

Methodology and Instrumentation

Sample Preparation:

• Ground cannabis flowers (0.5 g) spiked at 200 ppb and 1000 ppb levels
• Extraction with 5 mL acetonitrile using mechanical grinding and centrifugation
• dSPE cleanup with MgSO4, PSA, C18, and graphitized carbon black
• Filtration prior to analysis

Instrumentation:

• Waters ACQUITY UPLC H-Class System
• Xevo TQ-S micro Tandem Quadrupole Mass Spectrometer
• XBridge BEH C18 XP Column 2.1×100 mm, 2.5 μm
• MassLynx MS Software with Quanpedia Database and TargetLynx processing

Chromatographic Conditions:
Flow 0.5 mL/min; gradient from 2% to 99% methanol with ammonium formate and formic acid; column at 30 °C; injection 5 μL.
MS Conditions:
ESI positive/negative, capillary voltage around 2.5 kV, desolvation at 450 °C, cone gas 50 L/hr.

Key Results and Discussion

• All 59 pesticides were separated within a 15-minute gradient
• Linear calibration curves (R2>0.990) from 6.25 to 1000 ppb in cannabis matrix
• Recoveries for most analytes fell between 80% and 120% at both spiking levels
• Limits of quantitation were below or at regulatory action limits (100–2000 ppb)
• Initial matrix suppression for late-eluting compounds was significantly reduced by dSPE cleanup

Benefits and Practical Applications

• Rapid and robust workflow suitable for high-throughput laboratories
• Minimal sample preparation reduces analysis time and solvent use
• Automated method generation via Quanpedia reduces development errors and setup time
• Suitable for routine quality control and regulatory compliance in cannabis testing

Future Trends and Applications

Continued expansion of regulated pesticide lists and evolving formulations will drive demand for more comprehensive multi-residue methods. Advances in high-resolution mass spectrometry and automation may further enhance sensitivity, throughput, and data processing. Integration with digital databases and machine learning could streamline method updates and data interpretation for emerging compounds.

Conclusion

The combined acetonitrile extraction, dSPE cleanup, and UPLC-MS/MS method effectively screens 59 Oregon-regulated pesticides in cannabis with high sensitivity, accuracy, and throughput. Its simplicity, robustness, and automated method generation make it well suited for routine laboratory operations and regulatory compliance.

References

• Legality of cannabis by U.S. jurisdiction. Wikipedia
• Oregon Guide List for Pesticides and Cannabis. Oregon Department of Agriculture
• Oregon Health Authority Technical Report on marijuana contaminant testing