@cyclopath Pure supposition. When I first came on at this facility the post processing was minimal and rudimentary. The SOP was also much different. The extractions they were doing at the time were much warmer. The coldest they got was about -10c, straight from a commercial freezer. At the time we were seeing significant precipitation of water soluble contaminants both during rotary evaporation and durring subsequent decarboxylation (for decarb oils). They stuck to flasks, burned on to beakers, and smelled and tasted atrocious.
At first all we knew about the contaminants was that the only way to get them off the wall of a flask was to wash them with warm water. While they would resist ethanol washing they would come off quite easily with warm tap water. Hence, we began describing them collectively as “water solubles.”
After doing some research on what they might be I honed in on denatured proteins and unraveled DNA. My assumption was not that the ethanol was absorbing the DNA but that the ethanol was carrying water from the extract, bringing the contaminants along for the ride, similar to chlorophyll micelles. Our theory was that the water we picked up in the extraction (which was a lot due to the temps we were running) was leaving behind the water solubles as it was purged away both azeotropicly with the ethanol in the rotary evaporator as well as boiled off durring decarb.
As I understand it ethanol precipitates DNA not due to insolubility but by reducing the amount of water available to hydrate the DNA. This concentrates the DNA into the remaining water, causing precipitation. This would seem to fit with what we observed in that as the water content fell we saw greater and greater deposits on the flask/beaker.
Long story short, we picked up the bentonite to help deal with the water solubles we were seeing. It was a dramatic difference. We have since greatly evolved our extraction SOP. We run much colder for much less time. I would surmise that alone would mitigate the water soluble issue by way of simply having less water picked up during extraction. However, beyond working well for water solubles the bentonite also provides a terrific fine filteration media. On the basis of “it ain’t broke, don’t fix it” I have not attempted to make an oil with just the new SOP. Whether I have water solubles to remove or not it sure does make the oil shiny.