Researching Quality and Yield issues for CO2 Extraction

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Does anyone have information on temperature and pressure profiles they wish to share, or tech documents outlining this information on cannabinoid/terpene extraction using CO2 super critical or sub critical extraction methods?

I found this patent pertaining to the CO2 extraction process. It outlines set points and post processing necessary for purification.

View attachment US7344736B2.pdf

Using scientific method… on my 5L 2000psi unit, I had a starting point given to me by Eden Labs: 120F, 1600psi. So, I ran sub lots holding the temp at 120F, varying the psi from 1000psi to 1900psi in 100psi increments. I took each sample to a certified I502 test lab in WA, and had the cannabinoid profiles done and the precipitated wax total in each extract. The results explained that as the psi value went up more plant waxes were solubilized in the end. I wasn’t finished in the study and selected 1000psi for my pressure and varied the temp from 70F to 140F in 10F increments. I then again had the test lab measure the terpene and cannabinoid profiles. It was found that more terpenes were saved at the lower temps. So my experiment shows me that if I want quality I will choose sub critical setpoints and if I want quantity, I will choose super critical. My next experiment will be to vary setpoints under sub critical parameters to see if I can selectively pull only terpenes.

Please explain why you use 120F and 2000psi. I didn’t want to push my unit to this setpoint, but my results showed as I increased my PSI setpoint I pulled out more waxes.

120f and 1000 psi is a gas phase, so I wouldn’t expect much there. While it’s true that more waxes are extracted at higher temps/psi, its not because they are soluble. They are simply washed out because of the volatile environment.

I didn’t end my search at 120F, 1000psi. I actually now use 70F, 1000psi. only because I haven’t hooked up a chiller to take the extraction vessel down past ambient. I haven’t done any research down passed 1000psi yet. I need to do more research myself about the different polarity and how it effects extraction.

If you run your extraction vessel at 120F / 2000psi, what do you set your collection vessel(s) too?

Depends on the system manufacturer, I’m a consultant now days so I work on many different systems. Liquid pump=700-900 gas booster=200-400.

1000psi and 70f is too close to a gas state for my tastes, density is too low.

I want the best quality and I’ve found that occurs slightly below 2000psi.
I often pull chlorophyll past 2500.

The solubility of THC in supercritical CO2 increases with both temperature and pressure up through 5000 psi at least and 140F. The solubility of CBD in supercritical CO2 plateaus at about 2500 psi and 130F. Chlorophyll becomes soluble in supercritical CO2 somewhere around 2900 psi at 104F.

Increasing pressure and temperature will increase your yield, but at the cost of a less specific extraction (waxes, oils, chlorophyll, etc.). You have to find your sweet spot with respect to what yield and quality you can accept.


H. Perrotin-Brunel, P. Cabeza Perez, M.J.E. van Roosmalen, J. van Spronsen, G.J Witkamp, C.J. Peters – Solubility of ∆9-tetrahydrocannabinol in supercritical carbon dioxide: experiments and modeling – J. Supercrit. Fluids 52 (2010) 6-10.

H. Perrotin-Brunel, M.J.E. van Roosmalen, M.C. Kroon, J. van Spronsen, C.J. Peters, G.J. Witkamp, Solubility of Non-Psychoactive Cannabinoids in Supercritical Carbon Dioxide and Comparison with Psychoactive Cannabinoids – J. Supercrit. Fluids 55 (2010) 603-608.

Omar, Jone; Olivares, Maitane; Alzaga, Mikel; Etxebarria, Nestor. Optimisation and characterisation of marihuana extracts obtained by supercritical fluid extraction and focused ultrasound extraction and retention time locking GC-MS. Journal of Separation Science, 36 (8), pp 1397-1404

Waters sells a phase monitor for supercritical solubility measurements; I am just starting to learn how to use it. Pretty much you load a pure component (THC) for example, pressurize it with CO2 and heat it to see when it goes into solution. It’s pretty cool, can’t wait to play with it more for extraction/fractionation method development.

what temperatures and pressures are your collectors at?

I am just now doing the metrics at the transcritical phase(1100psi@89.5f – 2000psi@110f).

I find that using the lower temperature/pressure runs yields a product of higher purity. Meaning the product extracted had less lipids/chlorophylls etc. On the con side of this equation, the CO2 acts less like a chemical/physical solvent (hcfc Butane, hexane, etc.) and more like an inert gas (physical solvent@scf). Thus the time required to extract what you need is higher. Our run time for these metrics were 16 hours at 7.8241% yields with a 93.4412% purity and a 6% terpine content. Pictures coming.
For reference separator pressure/temp:
S1-1100psi@85f. S2-850psi@75

However with these metrics I was never able to extract MidRun. the extracts would freeze up and I would have to heat up the separators to recover the oils.

I noticed that running higher pressures and higher temperatures/pressures extract everything faster and more as a liquid. Think of hot water dissolving and washing away oils. the hotter and the higher pressure dissolve or strip better than low. The fall back to this approach. Is that the time becomes the most important sensitive parameter. @15-20 minutes you may pull terps/oils-no waxes. And at 22m you start pulling chlorophylls and ruining you quasy vape-ready oil. The issue here is the sweet spot between the two.

For example if you start off the extraction right away at high pressure, what you said is true. This is because terpenes and residual water are still present in the plant material and acting as a secondary solvent to the CO2. This pulls out additional undesirable compounds.

If instead you start out at low pressure and drive off the water and terpenes, you can increase the pressure without pulling many unwanted components.

The picture below shows an extraction at 40C and 220bar on Waters BBES. It processed at 1.5-2 hr per pound of plant material (non-decarbed) and tested at 80% cannabinoids in the extract. The picture is of the collection vessel after draining the extract.


I believe one key piece that people are leaving out here is their mass flow of CO2, temperature and pressure is great to understand your density in gas or liquid phase, there is a useful tool shared with me by a professor at Stanford,

This can help those who are looking for an easier way to understand their densities, it breaks it down in liquid and gas phases.

So it comes down to mass flow and time, I’ve heard some good things with regards to low pressure pulls, haven’t tried many lower than 1000 myself, but over the next two or three days we are going after 300-900 psi pulls to see if we can seperate terpenes while retaining optical clarity. We have pulled high terpene fractions before, similar to the test previously posted, an yes there is some cannabinoid crossover. I know of a quality extractor in Colorado that has a terpene isolation process that yields amazing terpenes pre co2 extraction. I don’t know his process, he is however an amazing extractionist that knows his solubility coefficients like the back of his hand.

In regards to cannabinoids, we have obtained multiple runs above 85% cannabinoid content on a 12-15% w/w efficiency pull, the key for this is low and slow. I know that some people swear by high pressures, to each their own, some operate that way based on their machinery. CBD pulls faster than THC so if you want that quality look you MUST monitor your times closely or you can begin to pull a red fraction. You will pull red waxy fractions at the final phase of your co2 pull if your pressure/time/temp is too high (individually and combinatively)

I’ve shared conversations and some run time with folks running (factory? Cue waters specialist J) modified waters rigs (UV VIS detectors, a seperation column, etc) and those guys all love running high pressures because time is indeed money in this business. If you have the dollars to make that possible then you can save the time, simple as that. That UV VIS detector is one hell of a trick for those interested.

For everyone running pneumatic booster pumps, the pressure across each stroke is constantly changing from zero to XX set pressure. The machine is inherently less efficient because of the driving pressure and CFM it takes to buck the final 30% phase of the stroke is massive. A pump for a waters rig takes significantly less power to operate and it operates continuously at pressure. All in all a better pump design, though from my point of view their systems are undersized in terms of tubing, higher velocity gasses and solvents will end up leading to mechanically erosive conditions with all those fittings and bends.

For newbies, try 75-95F at 1200-1400 psi, you can fuss with the numbers upwards and downwards to change the selectivity.

For everyone else, remember that volatiles come off first, heavier constituents later. Depending on your starting material you will know what to do. There are some heavy leaning terpene strains (sour amnesia, cherry pie, etc) and some heavy cannabinoid strains (Most OGs, Chems, SOurs)

– Do a good job at pre extraction quality control and testing with UHPLC and scopes to determine if you have a heavy waxy plant.
– Recall that the stalk of the trichomes is not where the real “meat” exists, it is merely a conduit for the trichome head.
– Know that pulling your plants earlier yields a more transparent material.
– Know that improper curing and drying can yield a discolored material.
– Know that the musky smell of moldy material can transfer when extracting and that you must take steps to remove aflatoxins from your extract.
– Know that this is about understanding how to become a professional at removing components and isolating them to their purest form. But in doing so you can remove the “magic” or “soul” of the cannabis plant and its “entourage effects” or as some call it the “ensemble effect”

Think of cannabis as a plant with a symphony of molecules playing their part to create the overall experience of wonder and beauty.

co2 dissolves thca and thc at similar temps and pressure but thc is easier to extract so if u start with 50/50 material ur extract prob wont be 50% thca/50%thc unless u extract it for a really long time where the might even back out

i dont hav analytical numbers i just know that if i decarb i get ~ 20% more product for same time and amount of co2 used.

I’m an IES 2x5L. For THCa I run 900psi at 13C/27C
I’ve found my best overall yields on decarb’d material is 2320/33C also 1650/26C/42 works well. During the day i do a quick 5 hour run runs on high pressure 2850/42/47

I’m really looking for some input on THCa yeilding, i’m continually getting dry ice in my extraction cup, and i’m yielding about 150g off of 5lbs of material. Then i will decarb the material and run a THC run and i get the clearest most beautiful looking oil. I sent it in for testing on Wednesday I will let you all know the results that I find. But it’s an extremely clear oil. I’d like to here from anyone on THCa parameters.

Do you suggest to do a low pressure temp cycle (1200 PSI/70f) and than another with high pressure and temp (around 2200 PSI/120f)?
Or can i start with the 1200/80 and than slowly increase the temperature in the extraction vessel and thus also increase the pressure until i reach 2200 PSI at 120f?
will i ruin the terpenes extracted at the lower pressure if i do it all in a single cycle?

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