Filtered out the cannabinoids?!?!

So recently I was attempting to get closer to a clear color during predistillation filtration. I usually run my winterized crude and ethanol mixture through celite 545 and activated carbon.

The first jar is winterized, second is carbon scrubbed, and the third is ran through bottom to top celite545, t41, activated carbon, silica 60, and activated alumina.

After rotovaping back the clear jar I got back a few grams of dark oil/liquid?

Any advice to get to a more clear filtered liquid without removing all the cannabinoids is much appreciated. I’m a bit confused at what’s happening. Should I try flushing the column with heptane?


Still looking for answers if anyone has suggestions.

Heat will cause the etoh wash to darken.

I’m not sure what you are implying with this comment? I dont ever heat them up past about 100-120F. And it’s for about an hour or 2 during filtering through powders?

How much material did you start with

Filtration removes color (in this case), color/pigments have mass. You could do larger flushes at the cost of time and labor but why do you care to recover a few grams in the scale of 700-1000g of material? If you think the time, material and labor is worth it, you could save a bunch up and re-run it. Alternatively you could send it off for testing (~$75) and see if it is actually cannabinoids.

you most certainly captured some cannabinoids, flush the patty with warm solvent a few times, consider this secondary filtrate to be less pure than what you yielded in your primary filtration.


You used quite a lot of powder. The alumina could very well have just adsorbed all your cannabinoids in the solution… you said it took 2 hours to run the liquid thru that powder stack, have you tried eluting with fresh solvent to wash your product out of your powder stack.

Your using vacuum to pull your solvent thru and your using ethanol correct?


I’m running 150 grams crude into 1500ml of ethanol 200proof. What came through was about 2-3 grams after I recovered the ethanol. I’ve never seen nearly 99% loss through filtering so I’m super confused. I’ll try running another jar of warm etoh through.

Yeah rinse your media, it’s just stuck

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Rinse with an alkane if that diesnt yeild what you think it should.

You cannot expect your compounds to pass through the silica nor alumina as fast as they do through celite. It’s likely going to take a decent amount of solvent to recover I would not use heptane to get the oil back, that would take the most solvent., but would eventually work. EtOH and even ethyl acetate would be my choice to use the least amount of solvent. I would maybe use a very small layer of the silica gel and alumina moving forward.


Ethyl acetate would be best for flushing the column to recover product but the extract will probably come out not much different than it went it… at least you get it back and will be able to try again.

If the solvent he used to dissolve his extract prior to passing it through the powder stack was ethanol then its unlikely his cannabinoids are stuck in the silica gel. Most likely stuck in the alumina. If it was originally a heptane solution then its most likely stuck in silica gel.

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I appreciate all the insight coming in in the topic. Does anyone have a recommended filtering set up they recommend per volume? I have 180mm diameter funnels.

Well, this honestly confirms the suspicions I’ve had about yield loss due to crc. Some of the powders are absorbents and as such I was under the impression that they would hold on to cannabinoids regardless of any amounts of flushes.

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What alumina do you use? Mine are large grains, takes zero time to move through and once got some brown left, mostly slighty yellow more than often it’s still white.

I don’t typically use alumina. I like silica gel and I tend to use 240 mesh when possible to employ the smaller particle size. When using as a filter ‘plug’ it’s good to know how your will compound(s) adhere to it.

Definitely using large granules will keep your compounds from “sticking” That will also affect how well it cleans your batch, depending on what you are trying to remove. Definitely need to dial in the optimal parameters for your task.

I started using it because it was supposed to remove red pigments. I have not found this to be the case with etho. I haven’t tried alkanes with it though.

It would be a valuable experiment to see if mixing the filter agents all together and loading as a slurry (in EtOH). VS building layers of each.

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I think the adsporbant layers (silica gel, almunia) hould stay small and concise. The more I think about it…

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