Oregon Residual Solvent Analysis Method for Cannabis/Hemp using a Single Quad GCMS with Headspace

Importance of the Topic

Residual solvent analysis is critical for ensuring consumer safety and meeting diverse state regulations in the rapidly expanding cannabis and hemp markets. It helps verify product purity by detecting trace levels of process solvents.

Objectives and Study Overview

The method was developed to satisfy the State of Oregon’s requirement to screen thirty-five residual solvents in cannabis and hemp matrices. The goal was to achieve reliable detection and quantitation across a wide dynamic range in a single analytical run.

Methodology and Instrumentation

• Sample Introduction: Static headspace with a Shimadzu HS-20 autosampler; 150 µL sample in a 20 mL vial, equilibrated at 120 °C for 15 min.
• Chromatography: Shimadzu GC-2010 Plus with Rxi-624Sil MS column (30 m × 0.25 mm ID, 1.40 µm film); split injection 50:1; oven program from 30 °C to 200 °C over 16.3 min.
• Detection: Shimadzu GCMS-QP2010 SE in Selected Ion Monitoring (SIM) mode with 70 eV EI source.

Results and Discussion

The thirty-five solvents were separated into three SIM acquisition windows over a 16-minute run, enabling targeted detection. Calibration spanned 1.5 to 750 ppm by weight, showing slight quadratic response for some analytes due to matrix effects. Key performance highlights:

• Benzene LOD: ~0.05 µg in headspace (1.5 ppm by weight), below Oregon’s 2 ppm limit.
• Ethylene glycol LOD: 4 µg in headspace (~30× better than screening level).
• No detector saturation observed for high-level solvents up to 5000 ppm screening equivalents.

Benefits and Practical Applications of the Method

• Comprehensive screening of all regulatory solvents in a single analysis.
• High sensitivity and broad dynamic range support both trace-level and bulk solvent monitoring.
• Automated headspace sampling improves throughput and reproducibility.

Used Instrumentation

• Shimadzu GCMS-QP2010 SE
• Shimadzu HS-20 static headspace autosampler
• Rxi-624Sil MS column
• 20 mL headspace vials, heat-resistant septa and caps
• 0.2 mL deactivated headspace sample loop

Future Trends and Potential Applications

Advances in headspace automation, ultra-fast GC techniques, and enhanced data processing are expected to further reduce analysis time and improve quantitation. The method can be extended to other botanical extracts, food matrices, and pharmaceutical products to ensure residual solvent compliance.

Conclusion

The validated GC-MS headspace method fulfills Oregon’s regulatory requirements, delivering accurate, robust, and high-throughput analysis of thirty-five residual solvents across a wide concentration range. Its adaptability makes it suitable for diverse quality-control environments.

Reference

• Oregon Administrative Rule 333-007-0410: Table 4. List of solvents and their action levels