Chromatography through pH adjusted stationary phase


Anyone have any inklings on what might happen if we were doing chromatography (regular or dcvc) on pH adjusted alumina/silica? There’s some acidic and basic stuff from a supplier and i was curious on how it would effect column resolution (if at all?)

Also, I would assume the column would grow less and less acid/basic over multiple uses?


If using basic alumina, you might find your CBD runs through with a purple band due to some deprotonation/quinone formation - you can probably find more info around here about that. I’d definitely try it on a small scale to begin with. Could result in streaking and poor resolution. This is all speculative though.

Yes, eventually your basic alumina will go neutral. There are some reactivation procedures though. Good luck!



Was curious if it would make certain compounds “drag” a bit more. Or change the separation rates. Or if the polarity & charge are the only variables at play.

Generally if you have a protonatable/deprotonatable spot on your molecule of interest, like an amine or carboxylic acid, you will get streaking in regular silica. If you’re trying to column purify any of the cannabinoic acids (THCA, CBDA, etc), i would NOT recommend basic alumina. The carboxylic acid group will deprotonate and if it ever elutes, it will be as a salt. I’d use regular silica/alumina for regular old THC or CBD.

Theoretically I don’t think the compounds will ‘drag’ a bit more if you are using neutral THC/CBD. BUT consider that using acidic or basic stationary phase could make your actives isomerize (into d8-THC, for example), depending how long they’re being retained for. Would love to see your results.

Also curious - are you very familiar with column chromatography? If not I can provide an awesome reference.

All the best.


I’d love any reference you have :slight_smile:

I’ve done almost all my chromatography in a DCVC style. I started with methanol/hexane gradients. Then quickly moved onto an ethanol + water gradient with pretty great results.

My supplier sent me an acidic and a basic bag of alumina cuz they’re nice. But I wasn’t sure what to do with them :slight_smile:


jo00408a041.pdf (400.8 KB)

This is the simplest method of chromatography that uses the least amount of silica. I’ve used this method for years and it is tried and true. Good luck!