Thank you for your help!
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Would love to consult you or anyone else on chromatography if anyone needs it. I use chromatography daily to perform difficult separations.
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Can you reuse your solvent if you’re running your column dry between each mobile phase?
Can you rephrase that question, i dont recommend allowing your silica to become dry while separating and i advise wet loading
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I’m sure you’ve already looked into it…but…
DCVC with ethanol and water gradient over alumina is so damn easy and cheap. Ive only done 80g columns on 3" diameter, but I’m gonna move up to 12" diameter and shoot for 1kg runs.
If you’re not particularly worried about terps it’s pretty amazing.
You set the column once with a celite cake on top. I’ve used a single column a dozen times or more and no issues with the stationary phase. It’s so very easy.
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Also get heavy metals out too yeah.
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A new rabbit hole to explore
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What application is this system for? Seems very polar. Perhaps I’m missing something. Thanks for the reference to this technique.
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Would be awesome if I didn’t have to rotovape my solution today out my Celite. That takes another 2-3 hours .
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You run dry columns with a polarity gradient. Its considerably faster and uses much less solvent.
I usually have a small celite layer on the bottom.
Then 3-4" of alumina.
Then another 1" of celite on top.
If you’re wet loading. Take a 50//50 solution of oleo:ethanol and put it onto the celite and soak the cake (you’ll need to get a feeling for how much you can wet load into the cake) Once absorbed into the cake I run a flush of water over it to set it in place under vacuum.
I run my column cold so I can do it faster without worrying about boiling.
Then usually start with: (run them to dry Everytime)
1 part 60//40 etoh to h2o
1 part 70//30
1 part 75//25 (you’ll usually see some movement of your desired compounds 1/2 way down the column at this point)
2 parts 80//20 (bulk of your desireables)
1-2 parts 85//15
Then at this point either a 90/10 if there’s any desireables, otherwise just flush the column with pure ethanol.
Keep your desireables, evap solvent. Repeat as necessary!
The benefits are pretty huge.
Way cheaper equipment.
Way less solvent.
Much faster (15-20 minutes for a full column)
Never really need to setup or change your column (if using alumina) (so far I’ve got a dozen runs on a single column with no change). So big cost savings there.
You only ever need 3-4" of your stationary phase. And you could literally go as wide as you want. According to my napkin math I’ll be able to do about a kg with a 12" wide column.
I’m toying with the idea of using sprayers and doing a massive bed. You could automate it somewhat and go through tens of kilos per hour for super cheap.
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Good details. I love dry loading, I was taught to use silica so the celite tip from the video is ace.
You’re running cannabinoids with this system?
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Yeah it’s for cannabanoids. I think beaker had a video somewhere? Otherwise I’ll post one when get my bigger column in. I usually just do it to take a super ugly oil and make it shine. You can take the worst oleo and turn it red/gold in a single column pass.
I haven’t tried yet, but I’d absolutely assume you could isolate different cannabanoids on your second pass if you know what you’re looking for. You might need to go slower and use a more water heavy gradient to get really fine separation.
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I rarely use alumina. I didn’t realize it could handle what are essentially reverse-phase mobile phases and still get separation.
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I was super surprised at how good it works! You can get the same results with silica and using a polar/non polar gradient as well (methanol/heptane). I don’t use silica with ethanol/water simply because the silica will act as a dessicant and ruin your column over time.
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What are you removing with alumina and ethanol/water gradients?
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Why can’t you run a column in acetone? I was thinking about trying a water/acetone on alumina column…
Normal phase silica gel is dissolved by acetone. Other media is possible but not your typical normal phase silica
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Do you have a reason to use acetone? My uninformed guess is that it will not be selective enough to get a good separation, everything is just so dang soluble in acetone… But maybe someone figured out at acetone/non polar mix that gets good separation I dunno
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No reason really. Was just going to try it out and see what kind of separation I could get on alumina with DCVC.
Experimenting with purifying crude CBD oil.
If you play your cards right you will remove THC and also pull out gold oil using alumina.
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