Steam distillation of extract to further refine it

[eugeneoregon]

A youtube video showing my steam distillation rig.

 

[BobCajun]

I was watching your DCVC video and I was thinking maybe you could do it on a column of weed directly. Just pour down a ratio that pulls out the polar stuff, and discard. Then pour down the ratio that starts pulling cannabinoids and gradually increase until you get them all.

BTW, heptane is better than hexane for cannabinoids and has the benefit of not producing a harmful metabolite. A good combination I've read about is heptane/ethyl acetate.

But how do you like my idea, weed column chromatography? Or I guess maybe 2" of silica at the bottom and a foot or two of weed above it, and a vacuum to pull it through. It would just be more solvent than usual for DCVC. This would be called Dry Weed Column Vacuum Chromatography.

 

[eugeneoregon]

I was watching your DCVC video and I was thinking maybe you could do it on a column of weed directly. Just pour down a ratio that pulls out the polar stuff, and discard. Then pour down the ratio that starts pulling cannabinoids and gradually increase until you get them all.

BTW, heptane is better than hexane for cannabinoids and has the benefit of not producing a harmful metabolite. A good combination I've read about is heptane/ethyl acetate.

But how do you like my idea, weed column chromatography? Or I guess maybe 2" of silica at the bottom and a foot or two of weed above it, and a vacuum to pull it through. It would just be more solvent than usual for DCVC. This would be called Dry Weed Column Vacuum Chromatography.

The problem with an ethyl acetate/heptane solvent system used over an alumina column is the polarity. It is extremely non polar in any combination relative to a methanol system. The DCVC (actually more of a filtration) video you saw on youtube used my short column. I have a very tall buchner funnel (from Laboy on Amazon) that I pack with about six inches of alumina and leave about four inches or so for loading product and solvent.

The idea is to NOT introduce a solvent that is good at disolving cannibinoids at all. The idea of the solvent gradient is to progress in a direction of solvent polarity that goes from not allowing some components to pass the stationary phase of alumina while others do pass and are collected. My current strategy in DCVC as practiced in my tall column is to progress from extremely polar to non polar. I have used nearly every combination (although not nearly every gradient) of solvent systems that you can pick off of the solvent polarity charts.

By far methanol solved problems with my chromatography of this product that no other solvent can simply because it is the most polar solvent next to water that there is. I currently use this in combination (thus the gradient) with ethyl acetate as the mobile phase. If you pull something higher in polarity through, like ethyl acetate and heptane then there will simply be no seperation at all because the extract (in my experience) disolves so nicely in that combo that it simply passes by the stationary phase without pausing. Keep in mind that I use alumina and not silica gel.

Silica gel has been known to "melt" in a way and be deposited in the end product, especially in the presence of high concentrations of methanol. This might be urban legend, but the msds sheet on silica gel carries warnings about inhaling this stuff that sounds kind of nasty. Alumina, on the other hand, carries the same warnings as sand. Keep it out of your eyes and if you inhale it, like sand, you will cough. Alumina is a very hard substance and is used as the "sand" on sandpaper. It is used as the scrubbing agent in abrasive cleaning compounds. And of course it is used frequently in all forms of chromatography. I buy in bulk from amazon. There are two variants and both have the same properties, but one version is brown and the other white. I get the white because it is easier to monitor progress through the column this way. I currently use 200 grit size but plan to order 400 grit (much smaller particules) to see if seperation can be more defined. Ten pounds of the stuff is cheap if ordered as an abrasive. If you order officially labelled lab use alumina for chromatography it will do the same thing but your wallet will be exponentially lighter - and my whole purpose is to refine this stuff with common products easily obtainable (if possible).

In terms of health consequences of any of these solvents, the MSDS sheets are widely available and easy to understand. Let me share anecdotal experience - I used to pit crew for alcohol burning race cars (sprint cars) here in Oregon. They burn methanol. The main health risk is inhaling fume. However, let me assure you that the moment that fume even begins to approach toxic levels through inhalation that your body's gag response and the acute and INTENSE burning sensation experienced in eyes, nose, and throat will make it impossible to continue inhaling even if you wanted to. In other words, like so many other solvents, once you get a noseful of it (which will not kill) your body will revulse and you can no more keep inhaling it any more than you can keep inhaling smoke around a campfire when the wind blows it into your face.

The real hazard with these solvents is fire. Methanol has a much higher flash point than hexane, heptane, acetone, and others and it takes a lot of heat and much higher airborne concentration relatively speaking to ignite it. This is one aspect that makes it so good as a racing fuel - it takes many volumes more methanol to produce the same "explosion" in the engine than the more non polar hydrocarbon fuels and the high flash point avoids preignition on very high compression ratio engines. The advantage to this (and the reason the really high performance guys use it) is that it then makes it possible (and necessary) to run enormous amounts of fuel through the engine relatively speaking. The effect of substantially more fuel through each cylinder to produce the same pop that makes engines work is that the extra methanol fuel has a cooling effect so the engines don't burn up so fast (in theory anyways, however sprint car drivers seem to burn a lot up of engines anyway lolz - ANYTHING just to hear the cheering of the crowd, right?)

At any rate the methanol is safer to handle from a fire point of view, although I stock a quart of just about every solvent listed on the charts. I appreciate your approach to safety, but the selection of solvent based on the metabolites produced if ingested is for me irrelevent because I avoid exposure. I also place a self ban on smoking when I use them. I am EXTREMELY leary of hexane, heptane, and other low flash point solvents because the fume travels far enough and in concentrations high enough in open air to ignite easily. I once dried a tiny amount of alumina soaked with hexane in my oven. Big mistake. Once the oven reached the flash point of the hexane, the hexane ignited and blew the oven door open with a THUMP! There was such a tiny amount and it shocked me, but I learned why not to dry solvent in an oven... I had been lulled into a sense of security because I had used the oven many times to dry alcohol from extract which flashes at a much higher temp.

The short video I posted with my small buchner funnel cannot illustrate what happens as a very polar solvent changes to a non polar phase like my large column can and my next "lonely man at home with too much time on his hands" video will demonstrate the "magic" of this technique and visualizing what happens in DCVC is easier when you see it yourself.

As far as extracting directly on top of plant material I had thought of this too, however I had thought to use kief instead of ground up plant. Either way the problem that you will encounter is that the alumina will load up to the point that pulling solvent through by vacuum becomes impractical. Once the vacuum level needed to pull the solvent through all that biomass exceeds a certain point the solvent will boil into vapor which will happen as the excessive amounts of polar material pack on top of the column and solvent will be blocked and refuse to pass. I think it will work, but frankly the best place to install a column for initial extraction would be into the supercritical fluid extraction machines and pass the stuff across alumina while in a supercritical state and before exiting the machine. This is far beyond my capability, but trust me when I tell you that once full blown commercial operations are sanctioned by the feds that this is the way large producers will procede. The pressures make it viable and producing nearly pure thc right out of the blast tube would be possible. Multiple chromatography chambers with various stationay phase compositions and processed through at different temps and pressures inline and inside such a machine could easily harvest individual cannibinoids.

Keep ideas coming. You can get a small standard chromatography tube for under $40. I got mine from Ctech glass (a singapore company) and it is meant for qualitative analysis and very tiny amounts. but if you decide to attempt chromatography I suggest beginning with the simple and progrss to the complex. It is in the simple system that solvent systems and strategy are most easily and inexpensively explored.

 

[BobCajun]

I guess if you find methanol that much better than other solvents then you have a good reason to use it. That was actually the first solvent I used for extracts many years ago. Now I'm sticking with USP isopropyl, which I consider the safest of the 3 common alcohols, safer than ethanol. It just has a somewhat lower acute toxicity, which isn't a problem unless you were to drink about 250 mls. About the heptane/ethyl acetate, just something I had read about while researching chromatography a little, apparently not appropriate in your case though.

Here's something you could try sometime though, using an anion exchange resin, strong basic, to capture the THCA, which you then liberate by adding a strong acid in a solvent to displace it from the resin. It would have to be non decarbed material though. And btw, silica gel is not that bad on the lungs, because it's amorphous silica rather than crystalline. Microcrystalline silica is the bad kind, like dust from fiberglass insulation. Still, silica really is dusty though and certainly an annoyance and I have read that alumina does work well for cannabinoid chromatography so just as well. Anyway, I look forward to your future videos, I'm subbed up. You're the THC steam distillation guy, the one and only.