Oregon Residual Solvent Analysis Method for Cannabis/Hemp using a Shimadzu GCMS-SQ and Headspace Injections

Importance of the Topic

Residual solvents are common byproducts of cannabinoid extraction and present safety and regulatory concerns. Monitoring these compounds ensures product purity, protects consumer health, and aligns with state regulations such as those in Oregon, which specifies allowable levels for 35 solvents ranging from 2 to 5000 ppm.

Objectives and Study Overview

This study demonstrates a headspace GCMS method, based on USP 467 principles, for simultaneous quantification of 35 residual solvents in hemp and cannabis matrices. The method aims to achieve screening limits below those mandated by Oregon law while maintaining rapid throughput and robust performance.

Methodology and Instrumentation

• Sample Preparation: 150 µL of sample in 20 mL headspace vial, equilibrated at 120 °C for 15 min.
• Headspace System: Shimadzu HS-20 in static mode with heat-ahead function, 0.2 mL sample loop, vial pressure 125 kPa.
• Gas Chromatograph: Shimadzu GC-2010 Plus, split injection (50:1) from HS-20, Rxi-624 Sil MS column (30 m × 0.25 mm × 1.40 µm), helium carrier at 1.24 mL/min.
• Oven Program: 30 °C hold 3 min; +10 °C/min to 140 °C; +45 °C/min to 200 °C hold 1 min; total run 16.33 min, cycle 25 min.
• Mass Spectrometer: Shimadzu QP-2010SE in SIM mode, EI at 70 eV, ion source 200 °C, interface 300 °C, solvent cut 0.1 min.

Main Results and Discussion

• Sensitivity: Benzene detected at 300 ng headspace (0.3 ppm in 200 mg) well below regulatory limit of 2 ppm.
• Linearity: Acetonitrile and methanol show linear response across 0.293 µg to 150 µg; ethylene glycol LOD at 4 µg (30× below screening level).
• Group Analytes: Butanes, pentanes, hexanes, xylenes and other isomers reliably quantified at 10 µg headspace.
• Dynamic Range: Covers low-level toxicants (e.g. benzene) and high-level solvents (e.g. butane) within a single analysis.
• Regulatory Compliance: Method performance meets or exceeds Oregon’s screening limits for all 35 targeted solvents.

Benefits and Practical Applications

• High Throughput: Heat-ahead headspace autosampler reduces cycle time, enabling efficient screening of multiple samples.
• Broad Coverage: Single GCMS run quantifies a wide range of volatile solvents, simplifying laboratory workflows.
• Enhanced Selectivity: SIM acquisition provides low detection limits and minimizes matrix interferences.
• Regulatory Alignment: Directly applicable to cannabis, hemp and other botanical extracts under strict residual solvent limits.

Future Trends and Potential Applications

• Automation and Data Integration: Increased adoption of robotics and cloud-based chromatography data systems for streamlined reporting.
• Advanced Separation: Two-dimensional GC and alternative stationary phases for improved isomer resolution.
• Expanded Scope: Integration with pesticide and mycotoxin screening in cannabis QC workflows.
• AI-driven Analysis: Machine learning algorithms for rapid identification and quantitation in complex matrices.

Conclusion

The presented static headspace GCMS method offers a robust, sensitive and rapid solution for residual solvent testing in cannabis and hemp products. It delivers reliable quantification across a broad dynamic range, fully satisfying the stringent requirements of Oregon regulations. Laboratories can adopt this approach to ensure product safety and regulatory compliance while maintaining high sample throughput.

References

• Ioannou J, Winkler P, Wang M, Clifford B. Oregon Residual Solvent Analysis Method for Cannabis/Hemp using a Shimadzu GCMS-SQ and Headspace Injections. Shimadzu Scientific Instruments.