Ethanol/Alcohol Contaminate Build-Up

I’ve been trying to learn as much as I can about ethanol (alcohol) extraction. This forum has been very helpful and I’m impressed by the level of expertise available. One of the questions that came up for me has to do with the extent that alcohol used for extraction becomes contaminated over time with pesticides, fungicides, mold toxins (mycotoxins), and the like.

I know very little about chemistry but here’s what I’ve been able to figure out. Initially, I ran across the post Removal of Pesticides from Equipment. In that post, glassware was exposed to high levels of Myclobutanil, a “triazole fungicide”. I was curious so I looked into this a bit and found that triazole is soluble in both alcohol and water. As such, I could see how it could easily be extracted from the plant material into the alcohol. From that post, I tried to do some overall “digging” related to what extent chemical pesticides, fungicides and mycotoxins are extracted using alcohol.

This is what I think I’ve learned. The fact that alcohol is a “polar” solvent means it can, at a minimum, blend with (extract) a whole list of chemical pesticides that are polar in nature (soluble in water). When it comes to fungicides, most chemical fungicides are “polar” (can be dissolved by polar solvents like water and alcohol), so it would seem to me that alcohol also frees up chemical fungicides from plant matter. And in terms of mycotoxins, in Making the Connection Between Cancer and Mold Mycotoxins, they write “mycotoxins are oily, insoluble in water, and soluble in alcohol and propylene glycol”.

Now many pesticides are not soluble in water (insoluble) but some do dissolve in lipids (fat). In Types of Pesticides , they list four main categories of chemical pesticides, Organophosphate, Carbamate, Organochlorine, and Pyrethroid. Looking at organophosphate, in Biodegradation of Pesticides, they mention that organophosphates are “highly lipid (fat) soluble”. Given that fats and waxes naturally occur in cannabis, it would seem to me that fat soluble pesticides dissolved in the plant lipids are freed up by alcohol (this depends in part on temperature and time of extraction) .

Anyway, my point is that it appears that alcohol frees up many toxins from the plant material. Given that the same alcohol is reused on successive extractions, to what extent do these toxins persist and build up in the alcohol? When the alcohol extraction is run through a rotovap, do the toxins move along with the alcohol or remain in the boiling flask?

My guesstimate is that toxins do build up in the alcohol up to some upper threshold depending on the type of toxin, the level of contamination, the amount of fresh alcohol introduced on each run, and a long list of chemical reasons that I know very little about. Has anyone done testing to see the level of contamination in alcohol that has been run months on end through extraction, rotovap, and possibly short path distillation? Does anyone have experience with this? Any help would be greatly appreciated!

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There was a post saying crude and the distillate didn’t contain mycotoxins or mold, so I’d assume it stays in the alcohols. In that case… don’t drink your alcohol, only drink your weed oil.

Pesticides etc. Stay in your oil

Thanks tweedledew. Given what you said, it seems like it would be important to make sure to remove as much of the residual alcohol as possible after rotary evaporation using distillation or decarbing.

I believe most pesticides will remain in the oil, vs the ethanol. They tend to be fairly nonvolatile

We have been doing ethanol extraction for 3 years and I can confidently say the pesticides et al go through to the oil. We test our alcohol and have never seen it pull pesticides. Hope that hrlps.

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MagisterChemist and Procan1, that’s very helpful. Thanks.

It’s great to hear that pesticides aren’t an issue. Given what you’ve said, I bet that mycotoxins, like the pesticides, tend to remain in the oil. I’m guessing alcohol isn’t often tested for mycotoxins or fungicides.

As an aside, it would seem to me that doing a sub-zero extraction would help to minimize fungicides as alcohol tends to act non-polar at those low temperatures.

We actually see quite a bit of biomass this time of year with mold. The freezer and ethanol wash takes away the mold from the final product.