CO2, Cannabis, and Terpenes Extraction Information

Removing Pesticides from Cannabis Concentrates

Leo Zhou
Written by Leo Zhou

Cannabis concentrates have a problem with pesticides; Flash chromatography has been proven to remove pesticides efficiently.

Like any crop, cannabis plants are prone to pests and disease. Some of which include tiny leaf-sucking spider mites, which can spawn a new generation in less than one week, to powdery mildew, a fungus that forms a talcum-like coating on leaves and spreads rapidly through greenhouses. For every other agricultural product, there is a relatively clear solution: find a pesticide labeled for the specific plant or setting, and apply it according to the instructions.

This is not the case with cannabis. Discrepancies between state and federal laws have left cannabis farmers without any approved pesticides for use on their crops. As a result, some growers have taken the matter into their own hands, treating their plants with alarmingly high levels of pesticides intended for other uses1.

Many cannabis products contain pesticides at levels higher than what’s typically allowed for edible or smokable products.

Some cannabis farmers in California spray their plants with chemicals such as avermectin (used in Avid insecticide), myclobutanil (used in Eagle 20 pesticide) and bifenazate (used in Floramite). Exposure to these chemicals has proven toxic or even carcinogenic; resulting in symptoms including vomiting, rash, nosebleed, tremors, and coma.

In some cases, up to 80 percent of cannabis concentrates that are tested show signs of pesticides. Of particular concern were the concentrates used to make candies, baked goods, and other edibles. Examples include samples of cannabis concentrates with levels of carbaryl as high as 415 parts per million (by comparison, the tolerance for carbaryl on blueberries is three parts per million). Carbaryl is a chemical typically used on fruits, vegetables, and ornamental plants. As well as Myclobutanil, a fungicide used to fight powdery mildew on vegetables, fruits, and leafy greens, was found between 44 and 392 parts per million in concentrates (levels allowed on food items usually range from 0.1 to 10 parts per million)2.

Some states such as Oregon and Washington, already have state regulations, which permit 100 parts per billion to 2,000 parts per billion, depending on the compound. Under California’s Medical Marijuana Regulation and Safety Act, passed last year, state oversight (including mandatory product testing) will begin in 2018. In the Medical Cannabis Testing Laboratories Initial Statement of Reasons, each pesticide is identified with the California Pesticide Residue Monitoring Program minimum detection limit and the reason for concern. For example, Myclobutanil is 200 parts per billion and Carbaryl is 100 parts per billion3.

Making pesticide-free concentrates is becoming critical. Flash Chromatography has been used to purify mixtures in pharmaceutical and chemical industries for decades; including natural product separation and isolation. Chromatography separation, based on compound polarity, is the most efficient way to purify a complicated mixture such as cannabis concentrates.

To address this concern, a study was initiated utilizing the BUCHI Reveleris® X2 Flash Chromatography system, C18 as the stationary phase, and Ethanol/Water as the mobile phase. The methodology developed proved successful in removing pesticides from concentrates as detailed in the table below. The residue testing report shows the pesticide content before and after purification using the Reveleris® X2.

The total pesticides have been reduced from 365,854 PPB to 708 PPB. Main residues such as Bifenazate, Carbaryl, Malathion, and Myclobutanil have been completely removed. Permethrin appears to be the most challenging of the pesticides in this study to remove since this compound’s polarity closely resembles that of THC, but it was significantly reduced after the purification. We believe that Permethrin residues can be reduced to allowable levels by further optimization of this method.

cannabis concentrates

Flash chromatography is a very efficient way to remove pesticides.

Based on the results, we are confident that we will be able to help producers in removing pesticides from cannabis concentrates to make healthy, safe and valuable products.

1 Borel, B. The Wild West of Marijuana Pesticides. The Atlantic [Online]. Aug 31, 2015. (accessed on Sep 19, 2017).
2 Margolin, M. Cannabis Concentrated Have a Problem With Pesticides. LA Weekly. Feb 27, 2017. (accessed on Sep 19, 2017).
3 Bureau of Marijuana Control, Testing Laboratories Initial Statement of Reasons. Bureau of Marijuana Control: (accessed on Sep 19, 2017).

About the author

Leo Zhou

Leo Zhou

Leo was born in Shanghai, China. He has more than 15 year’s experiences on Traditional Chinese Medicine-extraction, purification, and identification. He moved to California at 2013, working with Buchi Corp to support users with machine application. Cannabis process is very similar as Traditional Chinese Medicine, Leo is very happy to use his knowledge and experiences to help this industry.

Leave a Comment


  • @ExtraktLAB has the solution. It’s called Pure99 – preparative chromatography system – with no shortage of material, produce 125-150 KG of 99.9% pure isolates every month. Even more important, ExtraktLAB & United Science have developed the methods for pesticide remediation using Pure99 as well. Check out ExtraktLAB and reach out directly to Sales Manager Conor @ 651.398.2890 /

  • Leo, if you approve of using poisons on Cannabis because you believe you can clean up most afterwards is why you do not belong in the Cannabis industry, or to be an author of articles advising those that are. Change or get out of the industry is my honest advice, your advice is harmful to the industry. And growers, do not use poisons they are just wrong for Cannabis, people and the planet.
    Also I have grown Cannabis by the acre for 50 years and do not use pesticides or fungicides on crops, just use IPM it works and is safe.

    • Dear Mr. Watson,
      Clearly you missed the point of the article. Test results do not lie. Maybe you don’t use pesticides, but its quite obvious that many growers do. The article speaks to how technology can help remove those chemicals. If you can’t handle the direction that the future of cannabis is going, maybe you should get out of it, instead of the author. Therefore, you should have spent more time in a reading comprehension class and not getting high on your own supply.

      • Thank you both for these detailed responses, you’re correct Dr. Johnson, pesticides are in cannabis whether we like it or not. With this post, Mr. Zhou is not advocating for the use of pesticides but simply hoping to provide a solution to a problem that the scientific and cannabis community are still working to solve.(ie. how the pesticides are reaching plants grown in otherwise pesticide-free conditions) Along that note, I urge you both to check out the research that Steep Hill Labs has released regarding pesticides being introduced through the mediums used in root propagation. This was news to many growers. Check out more about that here:

  • Thanks you for an excellent paper. I hope you publish it in a journal soon. I accept that this appears to be a good technique in respect of the removal of pesticides from cannabis concentrates (oils). We need to keep up on making sure this subject does not fade away!

    But what about the removal of PGRs (Plant Growth Regulaters) such as 1-Naphthalene Acetic Acid (NAA) or the indole-based PGRs? I know that at least NAA is used to increase the cannabis ‘bud’ (flowers) growth rate and size by some growers! Here is a list of NAA derivatives which I have identified here Down Under here in Australia as present in 8 samples of cannabis oil in the last 6 months using Gas Chromatography Mass Spectrometry (GCMS)!
    1-Naphthuric Acid (most common)
    1-Napthalinoxocarboxylic Acid (next most common)
    1-Naphthalenecarbonylchloride (rare)
    1(2H)-Naphthalenone (rare)
    Trimethylsilyl-1-Naphthylenecarboxylate (rare but being a trimethylsilyl- ester probably involves contamination by silicone greases as used e.g. on the ball valves of a butane rig)…..

  • I posted a polite technical comment about trying to do an equivalent ‘scrubbing’ (to that of pesticides) of PGRs (Plant Growth Regulaters) such as Naphthalene Acetic Acid (NAA) and their derivatives noting the results of my own GCMS studies of NAA derivatives in cannabis oils But after my comments being up for 24 hours awaiting review TerpenesandTesting.Com wiped them! Please explain?

    • Good afternoon Dr. Short,

      My apologies that your feedback played a disappearing act. I assure you that T&T did not purposely delete them. We certainly value feedback from our readers, and I have personally approved of your commentary. Please let us know if you do not see your comments available on the site. Thank you kindly for letting us know they got removed.


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