Overcoming Challenges Associated with Analysis of Pesticides Regulated by Colorado State in Hemp Using a Novel LC/MS/MS Method with Dual ESI and APCI Source

C.E. Credits: P.A.C.E. CE Florida CE


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 products is important for consumer safety and quality control. Different states in USA and Canada regulate different number of pesticides with different action limits in hemp.  Among different states in USA, Colorado has issued most stringent regulatory limits for 102  pesticides residues in hemp products. In addition to pesticide residues, Canada, Colorado and other USA states also require hemp and cannabis products to be tested for 5 mycotoxins (4 aflatoxins and ochratoxin A). Normally pesticide analysis in hemp and other food matrices is done by both GC/MS/MS and LC/MS/MS since some nonpolar and chlorinated pesticides such as pentachloronitrobenzene, etridiazole, fenvalerate, iprodione, chlorfenapyr and others are difficult to ionize with electrospray source used in LC/MS/MS systems.   We would demonstrate how we measured these compounds at low levels using LC/MS/MS with APCI source to meet action limits for 102 pesticides regulated by Colorado state in hemp. The ionization mechanism of chlorinated pesticides such as pentachloronitrobenzene and others using LCMSMS system with APCI source would be presented. 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 ion suppression and matrix effects from hemp matrix to achieve lower detection limits to meet Colorado state action limits for 102 pesticides and 5 mycotoxins in hemp matrix. Sample preparation is the main bottleneck for achieving the high throughput analysis of pesticides in cannabis and hemp testing labs. For sample preparation, we used automated solvent extraction since it is quicker, simpler, cheaper, greener and easier way to achieve high extraction efficiency for pesticides in comparison to other time-consuming, difficult and expensive sample preparation techniques like solid phase extraction (SPE) and QuEChERS with dSPE( dispersive solid phase extraction) which show poor extraction efficiency. We added a number of internal standards to compensate for matrix effects in order to achieve method accuracy in range of 70-120 %. 

Learning Objectives:

1. List of Pesticides and their different action limits in different USA states and Canada for hemp/cannabis.

2. Analyze non-polar pesticides using novel LC/MS/MS method with dual ESI and APCI source.

3. Discuss ionization mechanism of non-polar pesticides with APCI source in negative ion mode.

4. Discuss mitigation of hemp matrix effects with LC and MS method optimization to improve method sensitivity to meet Colorado state action limits for 102 pesticides and 5 mycotoxins in hemp matrix.

5. Explain the rationale for selecting sample preparation method as automated solvent extraction with good extraction efficiency, less cost and higher throughput. 

6. Discuss addition of Internal standards to improve method method accuracy.

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