Opinions offered by the all knowing one generally suggest buying ones C18
However;
One way is to use a chlorinated silane to bond the C18 (Kirkland, 1970).
Alternately, halogenate the silica with thionyl chloride, then react this with a C18 (or C8) Grignard reagent (Locke, 1972; Brust, 1973). The silica will need to be heated to 300 °C to remove all water before the reaction, and all the HCl needs removed before the Grignard reaction
Which is almost over my head and certainly not on my list of to-do’s…(o-chem was a million years ago).
If there was an easy way to say bind CB1 to silica, that I might take on…
you may be able to get away with etOH as well, I haven’t played with it tho
Figure out what 1 column volume would be for your sys and read some analytical papers where they sep out a bunch of cannabinoids. method transfer from there. lead me to some success! if you’re doing just cbd from thc that should be relatively easy man! they like to space out from each other. Now if we’re talking some minors, that’ll take more work and I’d suggest 50 mM ammonium formate in the aqueous phase.
after ur done run 3 CVs of your B (B being MeOH/etOH/Hexane/ect.) thru the flash column and keep it fluidized! I’m trying that out to extend column life, so can’t tell ya for how long you’ll be able to get away with that.
c-18 for thc-cbd separation I would use 83% meoh and water for a quick and easy separation.
If you want better separation but more work do 70% meoh for at least the first column volume and then follow up with 83% this will get your cbd and thc band further apart and also yield a little better purity as the impurities will also be further apart.
Bonus trick.
Use TLC and figure out when your cannabinoids start to elute, as soon as cbd elutes switch from 70% to 83%.
I was going to say that methanol/water should be sufficient for THC/CBD separation on C-18 media. It’s what most flash chromatography systems use. If you are interested in an affordable flash system message me.
at about 55% efficiency on the first pass*** those reading papers and thinking that 90%+ separation at scale is achievable without several other steps haven’t done it at scale before imo. Or, at least, not with MeOH/diH2O. I don’t think chroma was ever the best route for d9/CBD separation, but I’m glad it paved a way for the tek’s equipment to get into the industry.
I haven’t seen one ran in person yet but Extrakt Labs’s prep hplc system uses a Pentane :ethanol (or ethyl acetate can’t remember)
90:10 mix in a 3:2 dilution. Not sure about the stationary phase but having no water to deal with is nice.
I’d be interested in seeing a lab running normal phase prep HPLC. If you extract in heptane, you could.condense solvent down to a 2:1 in heptane with solvent recovery membrane, and then pass directly to normal phase skipping distillation.
Roi: I ask you this question, because if you’re derivatizing and capping your own silica, you clearly must know what I mean.
1.) HPLC mode: Can you please give us an example: Length and width, packing material particle size, of a C18 column which is capable of loading a Kg refined crude per shot?
I am curious of the flow rates involved (liter a minute)
and the ultimate costs, (stainless HP column, high pressure pumps, prep scale detector) per Kg. (factoring in capital equipment costs, solvents, solvent recovery, labor)??
Or some similar data in your experience with C18?
My main concern is cost effectiveness. Waters at one time published a blurb about prepscale cannabinoids. Costs just seemed prohibitive due to the reduced loading capacity of C18. I’m not even sure normal phase prep-scale HPLC is worth it…in today’s market.
Say we are attempting to go from 80% pure THC to 95% pure THC by this methodology…is there any profit there?
2.)Even if your C18 experience is Flash…low pressure…
but prep-scale…is it worth it?
Novasep has some impressive looking systems, but is any one using these at scale?
If any readers know, please report. Is it profitable?
If so, what is the specific application?
Why would you choose reverse phase for a thc dominant oil though?
C18 is normally used when you wanna separate thc and cbd Because they are harder to separate on a standard phase column. If you just want to try and isolate thc there are much better options.
I think you have to follow the thread a bit.
With the price of CBD what it is…
is it worth doing a prep-scale silica- C18 reverse HPLC separation?
It is a money question.
Currently is anyone making money doing C18 RP separations
of cannabinoids…any phyto-cannabinoid
(tolling THC clean up…yes…is the only way I can think of.
someone else pays for it…) but why would you use RP?
The loading capacity is poor?
SMB and Centrifugal RP modes excepted.
If so, what is the application.?
curious…
thanks in advance.
@tweedledew It really depends on how well immobilized the functional moieties are onto the bulk solid stationary phase. Since C-18 (stearyl aliphatic functionality) has been in use for so long, I’m sure it is almost always fully immobilized on silica in commercial products. Its functionality occurs only through Van der Waals forces/interactions with other non-polar parts of molecules (moieties)… You can think of it as being similar to static electricity in its attractive & repulsive characteristics. The only way it could be ruined is if it were repeatedly subjected to conditions close to or beyond those in which it was made in the first place… like highly reactive halogen or sulfur groups and very high temperatures (300+°C). It can certainly get “dirty”, though, and since you cannot just have your friendly neighborhood gecko come lick it clean, you need to use solvent and acid/alkaline conditions to oppose the “sticking forces” of the various molecules that have passed over it.
Here is a guide that may help you to understand the chemical compatibilities of silica, itself:
No strongly alkaline materials or high pH (keep it under 9), especially when cleaning an older, more worn column of silica-based stationary phase. Also avoid pure deionized water, at least by itself. You should be fine using methanol, ethanol or ipa, especially in their anhydrous states. Acetone and even other ketones, ethers and esters should be okay. Go with what you know about your column’s history, trying to dissolve anything that has been through it, paying special attention not to react with those things (neutralization salts, polymerization catalysis, and those sorts of things are bad news)!
with C-18 modified , suitably capped to deactivate all the surface properties of the Silica (i.e. normal surface adsoption, binding isotherm), the operational concept of RP chromatography is liquid-liquid partition separation with
enhanced number of achievable theoretical plates (20-30 Kp/m) achieved by manipulation of physical considerations of flow and diffusion. Think of a separatory funnel filled with kerosene(c18) and methanol. The partitioning solutes for all intensive interactions only experience the “bound -liquid phase” and flowing mobile phase.
The bound liquid phase has a limited capacity to disolve solute…thus the limitations of the RP-C18 in the “preparative
scale” applications.
Almost every one gets their analytical separations done with
HPLC at one time or another. Virtually 100% of these separations are done with C18 columns. Cost? about $100 a shot for a microgram.
Considering costs involved (see above)and limitations of capacity is anyone doing Prep-Scale RP-C18 separations of Cannabinoids and making a profit?
just getting a few ferrules welded onto some kegs for liquid xfer and receiving. Hopefully by next week or so I’ll be in the $$