Isolating Cannabis Terpenes, Part II: Actual Process

[WaterFarmFan]

Wow - There are lots of types of Ether!!! Which ones of these would you recommend specifically for the application above?

http://www.sigmaaldrich.com/catalog/substance/diethylether74126029711?lang=en&region=US

Thanks again!!!

WFF

 

[WaterFarmFan]

Member Gry was kind enough to PM me and explain the difference in polarity and others between Diethyl Ether and Petroleum Ether, and that Petroleum ether was the suitable choice for this type of extraction. Thanks!

From wiki:

"Petroleum ether is the petroleum fraction consisting of aliphatic hydrocarbons and boiling in the range 35‒60 °C; commonly used as a laboratory solvent.[4] The term ether is used only figuratively, signifying extreme lightness and volatility."

 

[WaterFarmFan]

I found this thread relevant. Could anhydrous sodium sulphate be used without the ether? It is significantly cheaper, obviously less toxic and wouldn't require a purge. I believe this is a similar process to using the silica gel that I described earlier, but the chemistry is outside my scope of knowledge.

https://www.researchgate.net/post/H...r_extraction_of_oil_using_clevenger_apparatus

This has some good information as well.

https://www.researchgate.net/public...s_of_aromatic_plants_Future_economic_products

Another good read:

https://bioresources.cnr.ncsu.edu/r...and-hydrosol-from-picea-mariana-bark-residue/

 

[HashoftheTitans]

Have you tried centrifuging the hydrosol? You might not recover all the water miscible terps due to azeotropes but probably enough to be worth the trouble.

Or try to freeze the water out to separate the hydrosol?

I've wanted to try this but don't have a centrifuge so I will just have to wait until I have one available to me. I was considering buying a cheap one for this and separating thca from high-terpene extracts.

 

[G.O. Joe]

How many ml of ether would you add per 100ml of hydrosol solution?

The minimum. In this sort of extraction, 3-4x with 10% of the volume each would not be unusual.

Thus, it should be relatively easy to separate ether at low temperatures in order to not alter organic compounds. I think?

More worried about volatilizing than altering probably. Depends on the quantities.

Would you recommend evaporating ether via vacuum cold boiling or just sit out at room temp and evaporate with a non-heated stirrer? Would you recommend a chilled brine and ether at the same time for hydrosol extraction?

Depends on what it takes to get the solvent out. On second thought, ether has more solubility cold and less in warmer water because of the volatility and being the lighter layer. Salt still applies.

Wow - There are lots of types of Ether!!! Which ones of these would you recommend specifically for the application above?

I would use diethyl myself, but that's not exactly a recommendation.

Member Gry was kind enough to PM me and explain the difference in polarity and others between Diethyl Ether and Petroleum Ether, and that Petroleum ether was the suitable choice for this type of extraction. Thanks!

It may be perfect, but my suspicion is that the greater number of especially oxygenated organics are more likely to be very soluble in ether, less so for hexanes etc.

Could anhydrous sodium sulphate be used without the ether?

That depends on how it's used. This, silica gel, most other things all suffer from the problem of having a much larger mass than the desired fraction. Organic vapors can be absorbed but it's worth a try to remove the water in a desiccator on a tray above whatever desiccant.

Sorry I'm not really into links to javascript.

 

[WaterFarmFan]

Thanks for sharing your knowledge!!! I truly understand that an ether wash will be the most efficient means to capture water soluble terpenes and oxygenated organics, but I think that I will first explore a desiccant, salt and temperature based approach first.

Perhaps a workflow could be:

1.) Use Whatman #1 filter in vacuum assisted buchner funnel and add anhydrous sodium sulphate.

2.) Pull vacuum and add hydrosol to funnel. The idea would be to reduce the volume of h20 by 50%-75% (or more) but not completely to keep a workable solution volume - ("much larger mass than the desired fraction").

3.) Add filtered solution to separatory funnel or chromatography column with salt and use freezing temps and vacuum to assist separation. I would make a custom jacket that encases funnel or column made of flexible radiant barrier and connect an air line at bottom of jacket that pipes -10F air via a wort chiller submerged in glycol feed by an air pump with temperature controller and probe inside jacket. I could adjust temp in jacket by cycling off pump and watch separation with a simple lexan window secured with foil tape.

4.) Collect separated oil (and hopefully some organics) from top layer with pipette or running material slowly through bottom of funnel or collumn. Add a very small amount of anhydrous sodium sulphate to collected organic layer to desiccate any remaining water. Cover and chill.

5.) If the steps above are relatively successful with 80% or more capture of organics, I might stop, but if water layer still has strong aromatics, I might continue with further solvent, desiccant, chromatography and centrifugal techniques.

Thoughts on this? Thanks!

WFF

 

[G.O. Joe]

No need for salt a bunch of it (the sulfate) will crystallize in the freezer. Sounds like a mess and mechanical losses if not absolutely fubar in practice in my hands.

 

[WaterFarmFan]

No need for salt a bunch of it (the sulfate) will crystallize in the freezer. Sounds like a mess and mechanical losses if not absolutely fubar in practice in my hands.

Haha - me and fubar are friends. I just try to experiment in small batches so as to not waste much material. I ordered 10 lbs of sulfate for $15 delivered. Will test and report back.

Perhaps, a better solution would be to do the step #3 chilled separation sans any sulfate or salt? Would it make sense to only chill the lower portion of the separation device? Or you simply saying to put solution in a flask, place in a freezer and let separate?

 

[WaterFarmFan]

Finally have all the pieces and my cold traps assembled. Some elements are a bit crude, but this is DIY!!! I really love to use radiant barrier material, which is available at every big box store. It is flexible, which makes nice round shapes, but still rigid enough to provide some structure with really high R value for its density. I also use closed cell foam with adhesive backing in some places. And foil tape, lots and lots of foil tape...

Vacuum oven connects to top right of main cold trap via a 3/8" barb adapter. 1st stage cold trap is this model - https://www.ebay.com/itm/1000ml-24-29-Glass-Jacketed-Ice-Cold-Trap-Double-Layer-Chemistry-Lab-Glassware-/261958046841. For thermal jacket, I applied closed cell foam, sealed with foil tape and then double layers of radiant barrier. I made a lid for the cold trap using a porcelain evaporating dish that fit the top glass perfectly.

I use a vacuum take off adapter to a 250ml separatory flask. Adapter is insulated by simply wrapping RB around several times. I made a removable jacket for the separatory flask with a Lexan window to view collection. The idea is to allow the cold trap to cool glass and protect from room temperature. Not pictured, I will ran an air line to the base of the removable jacket. Air line is connected to submerged wort chiller and an air pump blows cold air to act as cooling bath of sorts.

Vacuum take off adapter is connected with platinum cured silicone tubing to second stage cold traps. Cooling bath basin is a professional 4.5 Qt stainless bain marie. It is triple wrapped with alternating layers of RB and cc foam (Foam, RB, Foam, Foil tape).

The primary lid is made from aluminum with holes cut for the 4x traps. When I add the tubing to connect traps, it torques the traps, so I built an aluminum riser that helps keep them straight in cooling bath. RB and lots of foil tape to connect aluminum pieces and sides. The lid drops over basin and forms a pretty tight seal, but gas and pressure can escape through the 4 holes. Another RB lid drops on top of the first to keep tubing area cold.

I have 4x themocouples in different places in the system. First is directly submerged in the cooling bath in 1st stage trap. Second measures the air temperature in the separatory flask jacket (I might use a temp controller to cycle air pump off and keep jacket area temp in a tight range). Third thermocouple is directly submerged in the stainless cooling bath basin, and the fourth is measuring air temp in the outer lid around 2nd stage trap system.

I will be beginning my test tomorrow with 1st stage temps ~ -30C using 70% glycol/30% ethanol and dry ice and 2nd stage temps ~ -78C using 95% isopropyl alcohol/5% ethanol and dry ice. First up will be a stupid terpy Cherry Chem (Cherry Pie x Chemdawg Bc3) from South Fork. I will cut and trim buds from the fresh plant (been waiting to chop her and is a bit past ripe - 25% amber now, but loud, loud, loud!!!) and process with ln2 using ptfe and stainless screens to break down buds. Stainless pestle and additional ln2 to finely crush buds. Once I begin processing, the flower material will never rise above 0C (likely stay much, much colder) before additional ln2 is added and it goes into vacuum oven for terpene extraction.

The real trick will be temperature ramps in the oven to the dry the material and release terpenes. I will repeat the process, by lowering oven temps and adding additional ln2 to flower material, until the material is completely dry. I will then perform a semi-standard (ultra low temperature) QWET extraction to get all the cannabinoids and then combine terps and shatter in various ways. I will also be testing using buds that have dried 3 days, 7 days and also long cured. Fresh might take more runs (and time) to dry material, but yield more terps. Time will tell, and so will I...

Here are pictures of the cold trap components and assembly in various states:

WFF

 

[WaterFarmFan]

Photos continued...

WFF

 

[WaterFarmFan]

I am having difficulty getting medical grade liquid nitrogen, but industrial grade seems more readily available. Given its properties as a very cold liquid (which I assume has to be pure), is there really any difference if I obtain the industrial grade at a reputable supplier for direct use on plant matter? Appreciate the guidance.

EDIT - Does medical simply mean that it is in a certified sealed dewar? I have my own dewar to fill.

WFF

 

[WaterFarmFan]

So, I really have been trying to wrap my head around all of the variables in the terpene extraction process, and it seems it really boils down to volatilization techniques - sublimation and evaporation. Freeze drying (lyophilization) uses repeated sublimation, and I found this informative:

http://vacuum-uk.org/pdfs/VacPlas_V... - 3rd Vacuum Symposium - Coventry - 2012.pdf (you have manually take off the s in https - bad Icamg!!!)

Vacuum ovens by nature have the heating element but not cooling. By freezing the material and it's container then pulling vaccuum, a single sublimation cycle happens first, followed by an extended evaporation cycle as the temperature ramps.

Now, I am starting to think about desired environment to achieve best results for each process. It seems that sublimation might happen best in a static deeper vacuum environment??? If so, the process might begin with pulling initial vac, back fill n2 to purge o2, and then pull deepest vac possible. ln2 sublimation will produce gas that the pump will fight to constantly bring down. After ln2 is gone (due to its boiling point), i assume h2o based sublimation will take place a bit later as temps rise???

The problem with a static deep vacuum is that condensation can form prior to making it my traps, but my working theory is that as I transition into the evaporation phase, I will begin to apply a lot more heat, which will cause any condensation formed from sublimation to eventually volatilize via evaporation and make its way to my traps (hopefully).

So, now the question becomes how high to ramp temps. From my QWET research, it seemed that the primary thing to avoid was pulling too deep a vacuum at high temps, which caused to Delta 9 THC to boil, but since I should be catching virtually everything in my cold traps (including d9???), is there a max theoretical temperature before terpene components are altered or damaged in any way?

A main process variable would be to repeat the cycle from beginning by re-chilling material or do everything in a single pass with a high enough temp. I suspect that fresh or semi-dried material will take multiple passes, but by pre-processing material using ln2 to chill and stainless screens to break up every piece (minus stems) below 1000 micron and then freezing a layer of distilled water on top of crushed material to aid terpene volatilization, I should get rather high surface area exposure.

I am sorry if my posts, including this one, are ill-informed or wrong in terminology. This is complex stuff, and it takes time, study and practice to grasp (for me). I know that I am newbie to practical chemistry, and part of my learning process is making posts like these. Thanks for reading.

WFF

https://en.wikipedia.org/wiki/Sublimation_(phase_transition)

Sublimation is the phase transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.[1] Sublimation is an endothermic process that occurs at temperatures and pressures below a substance's triple point in its phase diagram. The reverse process of sublimation is deposition or desublimation, in which a substance passes directly from a gas to a solid phase.[2] Sublimation has also been used as a generic term to describe a solid-to-gas transition (sublimation) followed by a gas-to-solid transition (deposition).[3]

At normal pressures, most chemical compounds and elements possess three different states at different temperatures. In these cases, the transition from the solid to the gaseous state requires an intermediate liquid state. The pressure referred to is the partial pressure of the substance, not the total (e.g. atmospheric) pressure of the entire system. So, all solids that possess an appreciable vapor pressure at a certain temperature usually can sublime in air (e.g. water ice just below 0 °C). For some substances, such as carbon and arsenic, sublimation is much easier than evaporation from the melt, because the pressure of their triple point is very high, and it is difficult to obtain them as liquids.

The term sublimation refers to a physical change of state and is not used to describe transformation of a solid to a gas in a chemical reaction. For example, the dissociation on heating of solid ammonium chloride into hydrogen chloride and ammonia is not sublimation but a chemical reaction. Similarly the combustion of candles, containing paraffin wax, to carbon dioxide and water vapor is not sublimation but a chemical reaction with oxygen.

Sublimation requires additional energy and is an endothermic change. The enthalpy of sublimation (also called heat of sublimation) can be calculated by adding the enthalpy of fusion and the enthalpy of vaporization.

https://en.wikipedia.org/wiki/Evaporation

Evaporation is a type of vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase that is not saturated with the evaporating substance. The other type of vaporization is boiling, which is characterized by bubbles of saturated vapor forming in the liquid phase. Steam produced in a boiler is another example of evaporation occurring in a saturated vapor phase. Evaporation that occurs directly from the solid phase below the melting point, as commonly observed with ice at or below freezing or moth crystals (napthalene or paradichlorobenzene), is called sublimation.

On average, a fraction of the molecules in a glass of water have enough heat energy to escape from the liquid. The reverse also happens — water molecules from the air enter the water in the glass — but as long as the relative humidity of the air in contact is less than 100% (i.e., saturation), the net transfer of water molecules will be to the air. The water in the glass will be cooled by the evaporation until an equilibrium is reached where the air supplies the amount of heat removed by the evaporating water. In an enclosed environment the water would evaporate until the air is saturated.

With sufficient temperature, the liquid would turn into vapor quickly (see boiling point). When the molecules collide, they transfer energy to each other in varying degrees, based on how they collide. Sometimes the transfer is so one-sided for a molecule near the surface that it ends up with enough energy to "escape" and enter the surrounding air.

Evaporation is an essential part of the water cycle. The sun (solar energy) drives evaporation of water from oceans, lakes, moisture in the soil, and other sources of water. In hydrology, evaporation and transpiration (which involves evaporation within plant stomata) are collectively termed evapotranspiration. Evaporation of water occurs when the surface of the liquid is exposed, allowing molecules to escape and form water vapor; this vapor can then rise up and form clouds.

 

[WaterFarmFan]

Success!!!!

Success!!!!

We have terps!!!

So, I have been experimenting this past week, and I finally had a breakthrough today. My previous attempts had some frustrating results, as I got some crazy delicious hydrosol that smelled almost identical to the flowers, but not too much in collectable terps. I think this has been the result of some others.

Well, I did two things. First was raise temps from 140-160F to 210-225F and second was to add a 300mm glass Graham condenser (cooled by ice water to ~2C) in front of my dry ice traps. I also streamlined my trap setup to reduce tubing (see below), as my first setup would only pull 28 Hg and the current does 29.5.

Higher temps really helped to volatilize terps. Condenser helped to pre-chill gases and convert many to liquid. However, the best thing about the condenser was after the run, I poured about 50ml of distilled water to collect any residue, and it was ABSOLUTELY loaded with terpenes. I noticed after about 4-5 hours that I was not seeing as much visible action in the condenser, and it turns out the reason was that the terps where condensating, sticking to the walls and staying in the loops.

I have been using liquid nitrogen to freeze flowers (submerged for 5-10 minutes) and then crush with a stainless screen and pestle into a stainless 9" high wall round pan. Ground material stays in the same pan throughout entire process. Once all flowers are processed, I pour a large quantity of liquid nitrogen into pan, place into vacuum oven and immediately pull vacuum. Vacuum pump fights very hard to pull down n2 gas as ln2 boils wildly in pan. Liquid nitrogen starts to solidify at around 24 Hg and starts sublimation around 26 Hg.

I then use several techniques to collect terps in traps:

1.) Deep Static Vacuum - This is what I have been doing first, or later as I restart the process to further dry, when I add the liquid nitrogen and pump finally pulls down. Usually 15-30 minutes.

2.) Slow Bleed - After 5-10 of static vacuum, I will slightly turn the nitrogen backfill (about a 3/4 turn on my AI oven), which is about 1-2 psi on regulator. This usually drops the vacuum level 1-2 Hg before it steadies.

3.) Hold & Clear - I turn off vacuum on oven (traps stay under full vacuum always) and backfill with n2 until vacuum reaches 1 Hg. I then let it sit for 5-10 minutes and then slowly turn vacuum knob to let vacuum level rise about 1 Hg every 2-5 seconds.

4.) Refreeze - After doing the above multiple times, I take the pan out of the oven and pour an additional large quantity of liquid nitrogen on material and start back at step 1. I repeat this entire process until the flower material is completely dry.

After all processing, I quickly disassembled all collection points and cap with a glass stopper. Terps and hydrosol are consolidated into one flask with minimal head space and sealed. I then rinse all traps with distilled water and collect into a single separate flask and seal.

A few additional notes:

Liquid nitrogen is fucking bad ass!!! The cooling power is unreal, and it will take the heat out of the vacuum oven in a hurry! I place the pan on a 1 1/2 inch slab of PTFE, and despite temps of 160F+, it was still cool to the touch after 2 hours where the pan touched.

I have been using around 10 cubic feet of nitrogen gas as a backfill per run. I added a tee with ball valves to fresh air, which I toggle to avoid wasting n2 when I am going to open the oven.

I have used a double wall stainless bowl in some tests and the results were confounding. When used with liquid nitrogen, the sealed air inside stays cold a long time. Oven temps can be 100F - 200F higher then the material in the pan. It is part of the reason that I went higher on my temps - metal temps in oven is different from the temp of material (heated by radiant heat in vacuum not direct).

Terpenes are insanely volatile! After I added the graham condenser, I could visually see what was flowing, and the hydrosol would drip clean but some terps would boil off as it hit an area exposed to room temperature after the condenser, but before the dry ice. A final point on this is that temps for collection vessels (and not just traps) must be very low to keep what you catch.

I am still separating terps in latest batch and will start to post hard numbers soon. I did run some fresh flowers and was a big pain the ass, as it took over 10 hours. I did do this first at lower temps, so I will try again in the 220F range and see if speeds up.

Here is latest version of the setup.

WFF

 

[Pangea]

right on WFF!

When you run fresh material do you remove the bulk of your h2o before you get to terp temps, or do you collect all at once?

Ive got a part 3 thread in the works that outlines how to put the process inline with the standard cls process, just waiting on some steeeeel!

 

[WaterFarmFan]

right on WFF!

When you run fresh material do you remove the bulk of your h2o before you get to terp temps, or do you collect all at once?

Ive got a part 3 thread in the works that outlines how to put the process inline with the standard cls process, just waiting on some steeeeel!

Thanks for the leading the way!!! I ran the fresh material for my very first run, which was under vacuum over 10 hours! I had my temps way too low doing multiple liquid nitrogen passes for the first 4-5 hours. I will do another run with fresh material this coming week, and ramp to the 220F range within an hour of starting. From my limited runs, and watching the terps flow, I think the heating method is better suited for large scale h20 removal versus sublimation. I also noted that when doing a collection, liquid that appeared as water seemed to flow first then always followed by spoty bursts of liquid that behaved more like an alcohol or oil, which seemed to pool and with less flow. So, I would deduce that water and terpenes are extracted at the same time and need to be dealt with accordingly. With cured flowers, I was using a 100ml or 250ml flask to collect directly from condenser, but with fresh I would go with a 500ml at least.

Another important aspect of making this practical for fresh material is to use > 0F temps in the first stage condenser to keep the h20 from freezing and blocking flow. Also, I noted that if I isolated trap system or dropped vacuum to 0 Hg in trap system, some parts would freeze solid, so I just never turn off vacuum.

WFF

 

[WaterFarmFan]

Another important aspect of making this practical for fresh material is to use > 0F temps in the first stage condenser to keep the h20 from freezing and blocking flow.

Sorry, I obviously meant temps above 0C.

I failed to mention that I do 2-3 minutes of ln2 grinding each time before that I put in the oven. I use (wearing cryo gloves) a stainless pestle and pour enough ln2 to just cover material. I think this has an effect on trichome walls to release terpenes.

It was a bit less than I expected, but I was able to collect 1.4 ml of terpenes from my last run. I was using material from previous runs, so I really can not say a starting weight. It was very difficult to get a clean separation without any water, so I just added a pinch of anhydrous sodium sulfate and it adsorbed the few drops of water (hydrosol), and then I sucked up oil using a syringe. It was a bit cloudy at first, but after 24 hours in refrigerator (in capped syringe), it is now crystal clear.

I have decided to go with twin 300mm Graham condensers in parallel, each with their own receiving flask. I think that this will increase throughput when dealing with n2 gas created from ln2 boiling in vacuum. It will also double my surface area for initial condensation and collection, which will be very beneficial when dealing with the large quantity of water from fresh material.

WFF

 

[WaterFarmFan]

I will say that I think this process is an absolute home run. I did a -50C QWET extraction on the processed material and it produced the best shatter that I have ever made. It was light amber, taffy above 90F and rock hard below. I added .15ml of my collected terpenes to a gram of shatter (after dissolving it in .3ml of Holy Terp Pure Flavorless), and it was BY FAR, the strongest dab that I have ever taken. Taste was mild but effect was devastating. Blew my testers away as well. Ended up mixing my collected terps at .05ml per gram, it came out so nice. It really has a much "fuller" effect versus shatter when I do side by side dab tests.

An interesting note is that after I mixed my collected terpenes with the shatter, the extract became VERY cloudy. Has anyone else seen this effect?

Will be processing more fresh and cured material this coming week. I will post detailed specifics about my starting weight, oven temps, collection times and total terpenes. Next test will have a double barrel Graham setup with glass connections.

WFF

 

[hash head]

couldn't you just mist some material with water and then vacuum purge but with an inline cold trap?

 

[hash head]

An interesting note is that after I mixed my collected terpenes with the shatter, the extract became VERY cloudy. Has anyone else seen this effect?

are you sere there isn't any water mixed with the terpenes you have collected? if there is would explain the cloudiness... think absinthe.. the residual ethanol from your qwet mixing with the residual h2o in your terp extract = cloudiness.

 

[hash head]

This may prove useful to those seperating water and essential oils (terpenes) .. if not already being used by everyone doing steam vacuum distillation.. or adding h20 to material and using cold trap as condenser..

https://www.ebay.com/i/112424040498?chn=ps&dispItem=1