Solving the Hemp Challenge: Pesticide Detection

With the passing of the 2018 Farm Bill legalizing hemp, farmers are allowed to grow hemp. Like any other agricultural crop, pesticides are applied to hemp plants to protect it from pests and improve growth yield. Chronic exposure to pesticides can lead to serious health risks and therefore pesticide analysis in hemp is important for consumer safety and quality control. Among all of states in USA, California has issued most stringent action limits for 66 pesticides residues in cannabis flower, cannabis infused edibles, concentrates and hemp.  Normally pesticide analysis in hemp and other food matrices is done by both GCMSMS and LCMSMS since some nonpolar and chlorinated pesticides such as pentachloronitrobenzene, chlordane and others are difficult to ionize with electrospray source used in LCMSMS systems.   We would demonstrate how we measured these compounds at low levels using LCMSMS with APCI source. The ionization mechanism of chlorinated pesticides such as pentachloronitrobenzene and others using LCMSMS system with APCI source would be presented. We analyzed all of 66 pesticides (including very hydrophobic and chlorinated pesticides typically analyzed by GCMSMS) spiked in hemp samples well below the action limits specified by California State. Hemp matrix is challenging and therefore it causes ion suppression and matrix inference for response of some of pesticides. We would demonstrate approaches to mitigate these matrix effects from hemp. Sample preparation is the main bottleneck for achieving the high throughput analysis of pesticides in hemp testing labs. For sample preparation, we used solvent extraction since it is a quick, cheap and easy way to achieve high extraction recovery in comparison to other time-consuming sample preparation techniques like solid phase extraction (SPE) and QuEChERS. Also, the performance of LC-MS/MS method was checked by conducting blind emerald scientific’s proficiency test for 66 pesticides in hemp. The proficiency test report generated with LCMSMS method showed acceptable results for all of 66 pesticides in hemp with no false positives and negatives.

Learning Objectives:

1. How to measure all of the pesticides (different polarities and molecular weight) with good sensitivity and selectivity in hemp matrix using LCMSMS method with dual ESI and APCI source?

2. Demonstrate that analysis of nonpolar pesticides (normally analyzed by GCMSMS) such as PCNB and others is selective, sensitive and linear using LCMSMS method with APCI source. Elucidate unconventional ionization mechanism of PCNB with APCI source.

3. Explain approaches to minimize matrix interference and ion suppression effects for pesticides from complex hemp matrix.

4. Present data to show that solvent extraction is fast, cheap and simple sample preparation method with good recovery for all pesticides to achieve high throughput in cannabis/hemp testing labs.

5. Present blind proficiency data obtained with LCMSMS method and emphasize the importance of participation in proficiency testing for cannabis/hemp testing labs to check the current status of their methods for pesticide analysis.