Glyphosate and… Cannabis?
25 Feb 2021By now, you’ve likely heard of Roundup. Roundup is the trade name for the broad spectrum herbicide developed by Monsanto in 1974 and it’s one of the world’s most widely used agricultural weed killers. Roundup and other herbicides like it contain a polar organophosphorus compound called glyphosate. Glyphosate is degraded predominantly by bacteria into aminomethylphosaphonic acid (AMPA). Another broad-spectrum herbicide that is very similar in structure and global use is glufosinate. The consumption of these compounds have been linked to severe health concerns including but not limited to cancer and concerns are being raised about these compounds contaminating crops, water, and other consumables.
Due to the polar nature of these compounds, these analytes are not retained by reversed phase chromatography which is typically used for routine pesticide analysis. To make these compounds more amenable to reversed phase chromatography they can be derivatized or an ion-pairing reagent can be used, but both of these methods have their own set of drawbacks. In this case, derivatization can be performed to add hydrophobicity to the compounds to achieve retention for reversed phase chromatography. The drawback of using derivatization is that it is oftentimes not complete and can potentially become quite labor intensive, adding cumbersome steps and overall time to sample preparation. Ion-pairing reagents are typically used when the compound is too polar to be retained by reversed phase chromatography. The ion-pair reagent contains an ionic head and non-polar tail, kind of like a soap. When added to the mobile phase the hydrophobic tail will interact with the hydrophobic stationary phase and the ionic head of the reagent can retain the polar analyte. Using an ion-pair reagent often results in the need to equilibrate for longer and the reagents are never fully washed from the column.
Recent trends in personal care product and food testing has shown the need to test for glyphosate, AMPA, and glufosinate to determine the potential risk for exposure. The Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO) has set a recommended acceptable daily intake of glufosinate at 0.01 mg/kg per day and the sum of glyphosate and AMPA at 0-1 mg per kilogram of body weight per day. (1)
But what does all of this have to do with cannabis? Glyphosate and glufosinate herbicides are currently not approved for use on cannabis crops. Though the use of these herbicides on cannabis crop may be unlikely, there could be potential soil contamination from other sources such as nearby farms contaminating the soil through run off. There could also be cases where contaminated ingredients are used to make cannabis infused products.
As mentioned previously, these polar compounds can’t be monitored by the same reversed phase chromatography that is used for pesticides currently. The Restek catalog of LC columns now offers Raptor Polar X as a solution to the direct analysis of polar pesticides. This column has shown its capabilities to retain glyphosate, glufosinate, and AMPA and has been tested in a variety of different matrices without needing to derivatize or use ion-pairing reagents.
The question remains, could this the next big thing for cannabis testing labs? Some third party labs have already started this type of testing for personal care products in order to label the products “glyphosate free.” Could “glyphosate free” be the next big selling point for cannabis products? I’d like to open up the comment section to hear your thoughts.
Interested in a certain topic and want it covered in the next blog? Send us an email with your cannabis laboratory/workflow questions and topics and it could be our next blog post!