Liquid-Liquid Advice

Hello Everyone,

I had a quick question for you guys regarding a liquid-liquid extraction. I perform THC remediation using a Gilson CPC and our “T-Free” Fraction comes out in an aqueous layer and an organic layer.

Organic layer is heptane and Aqueous layer is methanol and water.

We have cannabinoids in both layers and we are currently rotovapping both phases to fully collect the cannabinoids.

However, we are only able to reuse the heptane as it is not cost effective to separate the methaol from the water. So we end up disposing of freshly rotovapped MeOH/water.

Ideally we would like to find a way to separate the cannabinoids from the aqueous phase into the organic phase so we don’t have to waste time rotovapping MeOH/Water.

Some form of Heptane wash after adding polar solvent to the aqueous phase?

Any thoughts are appreciated.

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Yeah. Just keep washing the methanol layer with fresh heptane until the methanol tests clear.

Do you think I need to add more water to the mixture before washing with heptane in order to “push” the hydrophobic cannabinoids out of the aqueous phase?

Any tips on performing a good heptane wash?

Also, Thank you for your reply!

It will take approx 13 1:1 washes to fully strip the cannabinoids, I have a piece of equipment that I designed specifically for this operation that cuts the heptane solvent needs drastically- I’m actually using this particular LLE to clean a large volume of crude oil on a tolling gig next week with @RockSteady (I hope we are still on for it)

This particular operation is something I have spent a great deal of time on so feel free to DM me about it

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You do not need to add any water at all but I do to help with the heptanes efficiency yes, adding some acid will also enhance the efficiency of the process but be careful with heating an acidified oil.

My guess Since you are not Reusing your methanol
Would be to louche it all out by adding water 95%water 5%methanl
Almost all cannabinoids will jump to the
Heptane layer
@tweedledew is our Home LLE pro
See what he thinks

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Yah that’s what I’d do. Probably louche with brine to dehydrate your heptane layer otherwise you can get some water stuck in there.

Is there much for color in your methanol solution? You can get more color staying in the methanol with less water, but less heptane rinse needed with more water.

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Hey thanks for the reply!

So are you suggesting I bring the aqueous layer to a concentration of 95% water and 5%MeOH by adding more water? (Would DI water or distilled water be better or does it matter?)

Also I’m not sure what you mean by louche with brine could you be more specific for someone who’s never worked with brine in this fashion. Thanks again.

Also yes our aqueous layer is a slightly golden/pink color but when I add water it will turn a white/milky color. What are your thoughts on this?

Add the heptane first to the methanol you want to clean. About 1:1. Then add (heavily salted) water to 15-20x your methanol volume while stirring the whole time. The cannabinoids will hop over to the heptane.

Distilled is likely better. But i doubt it would make a huge difference

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Our LLE expert say s it all
Thx @tweedledew :pray:

(&^%&)(*ing louchers!
:rofl::rofl::rofl:

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Deionized water is what we all should use for LLE AND remediation.
Just my 2¢
You can buy 55gallons for $120 or get the in-house setup to treat your lab RO water.

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https://ingredi.com/deionized-water-55-gallon-drum/?gclid=EAIaIQobChMI88LGk6HD5QIVipOzCh2sNwLwEAQYByABEgKUDfD_BwE#ManufacturerInfo

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As in no salt? Or just controlling what ions are in there?

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Lol although…idk maybe if you don’t store it properly it will get a lower acidic pH if younger air react with it.
I guess the best thing is use clean water but the more we collaborate on certain sops etc it’s nice to have a constant. It’s good practice but ya.
One thing about water extracted concentrates — be sure they have clean water or you can get that ecoli patty. Not sure if dabbing kills that but the labs should start testing for those too

No saline is great. Add that to your water. You can put these little breathers on your tank that prevents the Co2 from acidifying your water - I can look it up I forgot

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I wanna say calcium oxide expansion tube (CaO).
@Photon_noir?
Or if you let water get to it and ph goes below 7 you can boil out the Co2 and bring the ph back to neutral. Sometimes you won’t get a reading depending on what’s you’re using because it’s deionized.

I realize that you’re adding salt and thus now it’s not deionized lol but start with proper water first.
I guess full circle if you’re going to add salt distilled might be same but it’s usually more expensive

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Get the rotochrom mixer settler, it’ll save you tons on solvent

How much do those usually run for?