Determination of Residual Solvents and Terpenes in Cannabis by GC-FID using Zebron™ ZB-624plus™ GC Column

Importance of the Topic

Cannabis products require rigorous quality control to ensure safety and compliance with regulatory standards. Residual solvents from extraction processes pose potential health risks while the terpene profile determines aroma, flavor and therapeutic properties. A versatile GC method that can analyze both classes of compounds in a single run improves laboratory efficiency and data consistency.

Objectives and Overview

This work aims to develop and demonstrate a single-column GC-FID method using the Zebron ZB-624plus column to simultaneously separate and quantify residual solvents and terpenes in cannabis samples. The study evaluates column performance for both low boiling permanent gases and high boiling terpene compounds under one analytical condition.

Methodology

Samples of standard mixtures containing seventeen common residual solvents and twenty cannabis terpenes were analyzed on a single Zebron ZB-624plus column. Key parameters included:

• Column dimensions: 30 m x 0.25 mm ID x 1.40 um film thickness
• Injection: split mode (10:1) at 250 °C, 1 uL sample volume
• Carrier gas: helium at 1.0 mL/min constant flow
• Residual solvents oven program: 35 °C (4 min), ramp to 50 °C at 20 °C/min, then to 160 °C at 10 °C/min, and to 300 °C at 15 °C/min
• Terpene oven program: 50 °C (1 min), ramp to 160 °C at 10 °C/min (hold 4 min), then to 280 °C at 12 °C/min
• Detection: flame ionization detector at 240 °C for solvents and 300 °C for terpenes

Used Instrumentation

• Zebron ZB-624plus GC Column (Phenomenex, 30 m x 0.25 mm x 1.40 um, Part No. 7HG-G040-27)
• Z-Guard pre-column for column protection (Part No. 7CG-G000-00-GHK)
• Zebron PLUS Straight Z-Liner (Part No. AG2-0A03-05)
• GC system with FID detector (250-300 °C range)
• Helium carrier gas supply and standard autosampler

Main Results and Discussion

The 624plus column achieved baseline resolution of seventeen residual solvents including light gases (propane, isobutane, butane) and heavier organics up to o-xylene. High selectivity of the 624 phase and low column bleed at elevated temperatures enabled clean separation. Twenty terpenes from alpha-pinene to alpha-bisabolol were also resolved in a single run without column change due to the column’s high temperature tolerance and thick film capturing low boiling compounds and eluting heavy terpenes at up to 300 °C.

Benefits and Practical Applications

• One-column method reduces instrument downtime and simplifies workflow
• Meets USP <467> guidance for residual solvents and provides reliable terpene profiling
• High efficiency and low bleed improve sensitivity and peak shape
• Applicable for quality control, regulatory compliance, and product branding
• GC-MS certified phase allows method transfer to mass spectrometry detection

Future Trends and Possibilities

The integration of this one-column approach with mass spectrometry and automated sampling will enhance throughput and compound identification. Emerging trends include multi-residue methods combining cannabinoids, pesticides and contaminants on a single platform, along with the development of new stationary phases offering lower bleed and higher selectivity. Portable and in-field GC solutions could further expand on-site analysis capabilities for rapid cannabis testing.

Conclusion

The Zebron ZB-624plus column provides a robust, versatile solution for GC-FID analysis of both residual solvents and terpenes in cannabis using a single method. Its high thermal stability, selectivity, and efficiency streamline laboratory operations while ensuring compliance with quality and safety standards.

References

• Dhandapani R., Aqeel Z., Krepich S. Determination of Residual Solvents and Terpenes in Cannabis by GC-FID using Zebron ZB-624plus GC Column. Phenomenex Technical Note TN-2077, 2018.