Optimization of Sample Preparation for Pesticide Analysis in Oil-Based Cannabis Products Using LipiFiltr®

This application note outlines the performance benefits achieved with UCT’s LipiFiltr® cleanup cartridge for the analysis of pesticides in oil-based cannabis products using LC–MS/MS analysis. The pesticides evaluated in this study include those listed in the Oregon monitoring list (≈60 pesticides). Cannabidiol (CBD) oil was used as the representative matrix. A comparison of pre- and post-LipiFiltr® cleanup using full scan GC–MS is also presented to demonstrate the removal of lipid co-extractives, without compromising cannabinoid content.

Procedure

Sample Extraction

• Weigh 1 g of sample into a 50 mL polypropylene centrifuge tube.

• Add internal standard(s).

• Add 10 mL of extraction solvent (90:5:5 [v/v] acetonitrile–

• water–toluene).

• Shake or vortex the sample for 1 h.

• Centrifuge the sample at ≥ 1500 rcf for 5 min.

• Pass 1.5 mL supernatant through a LipiFiltr® cartridge and collect the purified extract in an autosampler vial.

Instrumental

Pesticide Recovery

LC–MS/MS: SCIEX Triple Quad 6500 with SCIEX V Method™ for pesticides in cannabis    

Co-extractives Removal

GC–MS: 30 m × 0.25 mm, 0.25-µm Rxi-5Sil MS column with a Topaz Precision split inlet liner. A 1 µL injection volume with a split ratio of 10:1 was used.

Figure 1: Clockwise from top left: Comparison of hexadecanoic acid content, octadecadienoic and octadecatrienoic acids, and cannabidiol content pre- and post-LipiFiltr cleanup in a CBD oil extract.

Results and Conclusion

Pesticides

• Most compounds were found to have a recovery value in the range of 70–120%.

• A few polar compounds, such as acephate, exhibited low but reproducible (<10% RSD) recovery.

• Increasing the polarity of the extraction solvent or using a suitable isotopically labelled internal standard could be used to correct any discrepancy in recovery.

Co-extractives Removal

GC–MS (full scan) analysis showed significant removal of lipids and other high-molecular-weight matrix co-extractives using the LipiFiltr® cartridge, with no significant negative effect on CBD. This was backed up by LC–DAD analysis (not detailed here). While further work should be completed on other oil-based products, including those with a high THC content, the results highlighted here demonstrate that the LipiFiltr® cartridge can be successfully used to remove matrix co-extractives from oil-based cannabis samples without compromising CBD content or pesticide recoveries.

UCT, LLC
2731 Bartram Rd, Bristol, Pennsylvania 19007 USA
Tel: (800) 385 3153
Email:methods@unitedchem.comWebsite:www.unitedchem.com