Pesticides and Mycotoxins in Cannabis and Hemp
Cannabis and hemp concentrate products, including edibles, tinctures, extracts, and oils, have gained widespread popularity in the market. As the use of these products increases, the testing for pesticides and mycotoxins has become a critical regulatory requirement imposed by various state and national authorities. Pesticides are classified into seven major categories based on their intended field of use, including insecticides, herbicides, fungicides, rodenticides, acaricides, molluscicides, and nematocides. Given the harmful health and environmental impacts of most pesticides, their use is often highly restricted or banned. Mycotoxins, which are toxic secondary metabolites produced by certain fungi and molds, frequently contaminate agricultural crops, including cannabis. Therefore, reliable and accurate methods for the identification and quantification of pesticides and mycotoxins in cannabis products are essential to ensure consumer safety and compliance with regulations.
Overview
Legal and regulatory framework for Analysis of Pesticides and Mycotoxins
Cannabis is legal for medicinal and/or recreational use in various countries, including Canada, South Africa, Mexico, and many U.S. states, with several other countries evaluating its legal status. In December 2019, the U.S. Environmental Protection Agency (EPA) approved 36 pesticides for use in hemp cultivation. The application of pesticides is strictly regulated, and the residues in cannabis and hemp products are monitored by state agencies. The number of regulated pesticides varies by jurisdiction, with limits ranging from 10 ppb to 1 ppm. The U.S. Food and Drug Administration (FDA) sets a regulatory limit of 20 ppb for mycotoxins in human food and animal feed. Organizations such as AOAC are developing method requirements for cannabis pesticide analysis to ensure safety and quality control.
Safety hazards from cannabis contamination
Pesticides are widely used in cannabis cultivation to protect plants from pests and improve yields. However, chronic exposure to pesticide residues can pose significant health risks to consumers. Furthermore, the growing environment for cannabis can promote the growth of pathogenic molds and fungi, which can lead to contamination. Storage, transportation, and processing of cannabis also increase the risk of mycotoxin contamination. Mycotoxins such as aflatoxins G1, G2, B1, B2, and ochratoxin A are immunosuppressive, carcinogenic, neurologically toxic, and hepatotoxic. Consequently, testing for pesticides and mycotoxins in cannabis and hemp products is essential for ensuring consumer safety and maintaining quality control standards.
Methodology for the analysis of Pesticides and Mycotoxins
The analysis of pesticides and mycotoxins in cannabis products typically involves sample extraction, cleanup, standardization, calibration, and analysis using LC-MS/MS or GC-MS/MS techniques. These methods allow for the rapid monitoring of pesticide and mycotoxin residues in cannabis and hemp, ensuring that products meet regulatory and safety standards.
Sample preparation for pesticide and mycotoxin analysis
Analyzing pesticide and mycotoxin residues in cannabis presents challenges due to the complex composition of oils, terpenes, resins, and cannabinoids. The matrix interferences can cause substantial spectral overlaps and ion suppression, leading to inconsistencies in results. To address this, common sample preparation techniques include solvent extraction, QuEChERS, solid-phase extraction (SPE), and dilution. QuEChERS, adopted in the European standard for multi-residue analysis, and the updated QuEChERSER mega-method are particularly effective in analyzing pesticides in hemp matrices. Other techniques include liquid-liquid extraction (LLE), solid-phase microextraction (SPME), solid-liquid extraction (SLE), and dispersive solid-phase extraction (DSPE). To minimize matrix effects, dilution factors ranging from 10- to 100-fold are often used, with a 15-fold dilution effectively reducing signal suppression.
Preparation of calibration standards
Accurate reference standards are crucial for the precision of pesticide and mycotoxin analysis. Certified Reference Materials (CRMs) manufactured according to ISO17034 provide traceability, measurement uncertainty, and accuracy. These standards are essential for calibration, quantification, and system suitability. Calibration curves are prepared in blank matrix extracts, pure solvents, or by spiking plant material with a pesticide working solution. The concentrations of these standards should align with the detection limits of the analytes being tested. These reference materials are also used to assess matrix suppression, enhancement, and extraction recovery.
Pesticide and Mycotoxin analysis using LC-MS/MS and GC-MS/MS methods
LC-MS/MS is the preferred method for pesticide and mycotoxin analysis due to its superior selectivity and sensitivity, especially for residues with varying polarities and molecular weights in complex cannabis matrices. GC-MS/MS is highly effective for volatile and hydrophobic pesticides such as organophosphates and organochlorines. The use of analyte protectants can reduce matrix-related effects, and derivatization can enhance detection sensitivity. For multi-residue analysis, both LC-MS/MS and GC-MS/MS are employed, offering high sensitivity and selectivity for simultaneous analysis of hundreds of pesticides at low ng/g (ppb) levels in a single test.