Yeah, if you have analytics you can dial it down, otherwise those are probably a good place for you to start.
I’ve got a GC here, so I’m in luck 
I did a bunch of successful DCVC, so I think this will work. Gonna get a powerful UV light and make myself a little dark room to watch for separation I think?
Or will it be pretty obvious?
3 Likes
Oh Cyclohexane:DCM 8:2 may be worth investigating as well…
4 Likes
Felon to some Vet to others!
7 Likes
Can you just drop the chroma SOP or nah?
7 Likes
Cutting it close but should work
1 Like
Wanted to contribute some potential replacements for diethyl ether. Ethanol and ethyl acetate both work.
Ethanol isn’t very miscible in hexane but if you dig deep enough you’ll find examples of it being used. I think 2% ethanol 98% hexane is the mix reported. Not a lot of chemists have tried this because these solvents are reported as non miscible.
In my experience about 3% by volume ethanol with 97% heptane is about equivalent to 16% ethyl acetate by volume with 84% heptane. This % is about where the cannabinoids start flying off the column with normal phase on silica 60
Work with percentages of carrier solvent less than this and don’t overload your column. Any higher in % and you need a ton of silica to see any separation in my experience
10 Likes
I’ve got iso on hand. Will that work? Probably quicker even?
I wouldn’t get iso involved in your chroma.
Methanol is typically the alcohol used in chroma.
4 Likes
Yeah I figured it would just be really immiscible with the alkane though?
Isopropyl would probably work fine if it’s 99%
It’s a bit more non polar so I’m not sure how much you’ll need. Maybe a bit more than the ethanol needed but maybe not.
Unfortunately methanol isn’t miscible for these things.
I just realized you asked about this for THC/CBD separation. Is there a reason you picked normal phase instead of reversed phase?
3 Likes
Up front cost I suppose
I think regular phase silica will be about 1/8 the cost? Although it’s a moot point if it’s gonna make my life that much easier.
What are the main benefits of reverse phase in this application?
That’s true about up front cost but reusability is a nice feature of c-18
I haven’t seen normal phase used for industrial scale separation of CBD/THC. In order to get a good separation a restrictive amount of silica and solvent are needed in my experience
4 Likes
What solvent system works best on c-18?
I managed to reuse my silica fine with DCVC, what makes it non-reusable in straight phase?
You may be able to reuse silica 60 many times, just not many compared to c-18 bonded silica.
Best solvent system for that might be something like ethanol water with acetone for column cleaning.
I’m not sure what % is right for this
2 Likes
C18 is typically meoh/h2o or etoh/h2o
Clean with acetone or THF
@tweedledew - I would ask a real chemist, who is both cordial and knowledgeable in his approach, about such things, @Photon_noir for this bill and appears to have something to offer in other posts
4 Likes
That’s it right there…acetone is all it takes to flush C18 in my experience. Or THF. I prefer acetone
1 Like
For RP it is, but Methanol dissolves regular silica, so that’s a no-no.
RP columns are usually stored in IPA, surely can’t hurt then?
2 Likes
Good call!
Isn’t the IPA typically dried ahead of time?