We are starting to run a chromatography column to remediate thc from our cbd distillate oil. When we take our distillate and remix it to load 1:1.5. The color changes from golden to dark brown. Then we run through our column and it comes out gold/yellow and quickly turns back brown.
Does anyone know why it changes and how can we prevent or correct color back?
We use 200proof ethanol. As solvent.
Also I’ve read several places where people blend their solvent 70/30 etho/ water. What’s the benefit of using water? Besides the obvious of $$$.
Thanks guys. Feel like an idiot but just can’t figure out. Need additional brain power.
Maybe mix 1 mL of your EtOH with 1 ml of RO water and check the pH. Hopefully it is in the range of 6-7. I suggest this because the color of plant extracts is often pH dependent.
If you take a bit of the brown chromatographic eluent and put it in a cart, or put a few drops of it onto a stainless-steel table, is it still the same color brown?
I haven’t figured out a way around this. Any amount of time around ethanol will end up altering the pigmentation of distilled cannabis/hemp.
If you take your oil and let it sit in ethanol without running over a column it will probably change color similarly. I would time how long it takes to notice a color change and see if staying below that time threshold is reasonable for your process.
maybe some kind of ionic resin may do the trick instead of phosphoric.
this I don’t think would help the product that was being chromatographed as you don’t
want acid in the mix and you cant add a solid resin to it either but for storage or standing maybe.
If that brown pic is the mixture of distillate and alcohol, prior to injecting, it’s likely that your pulling oxygen into the mixture by vortexing too hard- try mixing at a slower speed and don’t pull a vortex down into your mixture. Water will make this worse. The combination of gentle mixing and swiftness between loading, elution, and recovery are crucial to the color- you could distill post-remediation, but make sure your cuts are perfect and take basically everything over besides the pigments and whatever is left in the flask when the color begins to darken- it’s not really going to be “tails” because it’s already 90%+ at this point. Check the PH of your solution coming out before recovery to prevent any unwanted conversion (if you’re going to distill), and find a sweet spot for the roto settings if that’s how you’re recovering the alcohol on your fractions to minimize residence time and exposure to heat and water.
Adding water to an ethanol solution of cannabinoids would cause the resin to precipitate as a milky microemulsion by a process commonly referred to as louching. It will not inhibit oxidation. Ethanol is very permeable to oxygen, is slightly acidic (speeding up the oxidation process), and allows the molecules of cannabinoids to swiftly move around to be contacted by the oxygen. This is a common problem. One way to mitigate it might be to sparge the ethanol with nitrogen prior to using it to dissolve the cannabinoid resin, and doing that dissolving under a blanket of similarly inert gas. After that, sealing the vessel without air is important, or even layering over the top of the alcohol with paraffin wax, like one would seal homemade jelly.
dur in my reading trying to learn more of rp chromatography I have come across the idea
of grinding divinyl gel then sizing it with a filter of set size.
this could also be done with the acid ionic variation of the gel and maybe if they were sized
and mixed together in the right mixture you would still be able to get the stickiness on the column
you need and a slight acidic environment to stop the phenol from colouring.
what that mixture would be I have no idea and if it would work I am still not sure but its an idea
anyway.
UPDATE: we ran all our dark thc remediated oil through a 2 stage wipe film. And absolutely nothing happened. It stayed dark brown. We are sending final product out for tests and I’ll report them here.
Has anyone remediated thc out of cbd full spectrum distillate? What color are you getting?
All come out dark. Hell the load turns dark before we even load it into the column
The samples are out for testing. Our internal GC reads 93% cbd. It’s crazy we can’t lighten it up. I’m thinking it’s not a contaminant it’s a color change in the oil. Baffled
We use glassware and pure grade ethanol out of plastic totes.
The oil turns dark just mixing it with the ethanol. We have tried carbon filtration, DE filtration. And even redistilling it. All for not. It stays dark.
I was just thinking with how fast the color change is you might have some residual base left in your glassware after washing. Especially if using a KOH/EtOH bath and not rinsing with 5% HCl followed by a lot of water.
Edit: Your picture looks very similar to CBDQ in alcohol solutions (usually appears purple but a red/brown/black is possible). If you have residual hydroxide in your glassware that is converting your CBD to CBDQ this hydroxide will be slightly retained on your silica media (correct me if using something else) which could be why it elutes from the column golden but quickly turns back in the receiving flask (due to residual hydroxide ions possibly present on your glassware).
