Journal:Screening for more than 1,000 pesticides and environmental contaminants in cannabis by GC/Q-TOF
| Full article title | Screening for more than 1,000 pesticides and environmental contaminants in cannabis by GC/Q-TOF |
|---|---|
| Journal | Medical Cannabis and Cannabinoids |
| Author(s) | Wylie, P.L.; Westland, J.; Wang, M.; Radwan, M.M.; Majumdat, C.G.; ElSohly, M.A. |
| Author affiliation(s) | Agilent Technologies, University of Mississippi, ElSohly Laboratories |
| Primary contact | Email: Philip dot l dot wylie at gmail dot com |
| Year published | 2020 |
| Volume and issue | 3(1) |
| Page(s) | 14–24 |
| DOI | 10.1159/000504391 |
| ISSN | 2504-3889 |
| Distribution license | Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International |
| Website | https://www.karger.com/Article/FullText/504391 |
| Download | https://www.karger.com/Article/Pdf/504391 (PDF) |
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This article should be considered a work in progress and incomplete. Consider this article incomplete until this notice is removed. |
Abstract
A method has been developed to screen cannabis extracts for more than 1,000 pesticides and environmental pollutants using [[gas chromatography] coupled to a high-resolution accurate mass quadrupole time-of-flight mass spectrometer (GC/Q-TOF). An extraction procedure was developed using acetonitrile with solid-phase extraction cleanup. Before analysis, extracts were diluted 125:1 with solvent. Two data mining approaches were used together with a retention-time-locked Personal Compound Database and Library (PCDL) containing high-resolution accurate mass spectra for pesticides and other environmental pollutants. In the first approach, a Find-by-Fragments (FbF) software tool extracted several characteristic exact mass ions within a small retention time window where the compound eluted. For each compound in the PCDL, the software evaluated the peak shape and retention time of each ion, as well as the monoisotopic exact mass, ion ratios, and other factors to decide if the compound was present or not. In the second approach, Unknowns Analysis (UA) software with a peak-finding algorithm called SureMass was used to deconvolute peaks in the chromatogram. The accurate mass spectra were searched against the PCDL using spectral matching and retention time as filters. A subset PCDL was generated containing only pesticides that are most likely to be found on foods in the US. With about 250 compounds in the smaller PCDL, there were fewer hits for non-pesticides, and data review was much faster. Organically grown cannabis was used for method development. Twenty-one confiscated cannabis samples were analyzed and ten were found to have no detectable pesticides. The remaining 11 samples had at least one pesticide, and one sample had seven detectable residues. Quantitative analysis was run on the confiscated samples for a subset of the pesticides found by screening. Two cannabis samples had residues of carbaryl and malathion that were estimated to be about 10 times greater than the highest U.S. Environmental Protection Agency (EPA) tolerance set for food and about 4,000 times greater than the Canadian maximum residue limits for dried cannabis flower.
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This presentation is faithful to the original, with only a few minor changes to presentation. Some grammar and punctuation was cleaned up to improve readability. In some cases important information was missing from the references, and that information was added.
