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Old 02-24-2010, 02:42 AM
BobbyDigital
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Default Detailed CO2 Extraction Instructions

http://www.google.com/patents?vid=USPAT7344736
Quote:
Abstract:
The invention relates to the extraction of pharmaceutically active components from plant materials, and more particularly to the preparation of a botanical drug substance (BDS) for incorporation in to a medicament. It also relates to a BDS of given purity, for use in pharmaceutical formulations. In particular it relates to BDS comprising cannabinoids obtained by extraction from cannabis.
This is the most detailed and thorough document I have ever read, and I enjoyed every word of it. Talk about the ultimate Cannabis extract! Supreme hash oil.

It's funny, though, how I would more than likely much rather just smoke a joint laced with dry sift of the original plant matter =) Something that potent is too much in my opinion. Although, seriously, that is cannabinoid extraction at it's finest, it doesn't get any more detailed or extreme than that.

(edit)It's basically the same document written two different ways, the first half is in lawyer speak, and the second half is in science speak. If you want a court document version read the first half, if you want a lab experiment version, start with the second half.

Last edited by BobbyDigital; 02-24-2010 at 03:20 AM.
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Old 02-25-2010, 11:18 PM
BobbyDigital
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Default Just the meat and potatoes =D

Here are some of the more interesting parts pulled out:

The advantages of using CO2:
Quote:
The applicant has selected as a preferred solvent carbon dioxide, which has a critical temperature of 31.1 C. and a critical pressure of 73.8 bar.

Carbon dioxide is particularly advantageous because it is available in plentiful supply, at low cost, and can if necessary be recycled. Any losses of CO2 are also ecologically neutral. Furthermore, CO2 extraction is a conservative method of preparation and quite fragile molecules can be extracted with precision.

A key consideration in the initial selection of liquid CO2 as the solvent for the production of a high potency standardised extract of cannabis herb was the high degree of selectivity which can be achieved. In the CO2 system it has been determined that solvating power can primarily be regarded as being a function of density and temperature, with the solvent density being the more important factor.
The plant and how it is grown:
They are not specific on the strain they are growing for their high THC chemovar, although they do say it takes 12 weeks to reach maturity, but they do no specifically say if this includes the veg stage or not. The plants are grown from cuttings of a known female mother, using compost as the medium, and fed with chemical nutrients, a base fertilizer and a slow release fertilizer, no pesticides/herbicides, etc.

Drying:
Quote:
The entire plant is cut and dried in a temperature and humidity controlled environment. Approximately 21 C. Approximately 38-45% RH. Dried plant is physically assessed for end-point.
This room is kept dark. Actually, from this point on, the material is always kept in the dark unless it is being worked on, and in that case, it is done under Amber light, so as to not degrade the cannabinoids by light. The drying process is about the only thing in the whole paper that is not scientifically measured, they just kind of guess when it is dry enough, no measurements are taken to determine exactly when they are dry, and no length of time is given. This is because when they store it after drying, it will end up maintaining a specific water by weight % under the storage conditions.

Storage:
Quote:
Under conditions of storage the loss on drying reaches equilibrium of approximately 10%.

General Storage Conditions for BRM:
Protected from light.
Approximately -15- -25 C. or -20 C.
Approximately 38-42% RH.
The first line is a little confusing, but what I think it means is that under these storage conditions, the plants will end up retaining about 10% water by weight. This is when the plant will cease to dry, or lose any more water. This happens when the material reaches the same moisture content of the air surrounding it, so it will not lose any more water to the air. So they do sort of measure when it is dry enough, and that is at 10% water, and this is maintained by controlling the atmosphere of the storage space.

Decarboxylation:
Quote:
THC and CBD are the principle bioactive constituents in Cannabis. However, these constituents are present as the biologically inactive carboxylic acids in Cannabis plants. In order to extract THC or CBD from cannabis plant material, it is necessary to convert the storage precursor compounds of THCA and CBDA into their more readily extractable and pharmacologically active forms. THC and CBD acids slowly decarboxylate naturally over time. The traditional way to increase rate ofdecarboxylation is by the application of heat. However, THCA is converted not only to THC, but also to another cannabinoid, cannabinol (CBN).

The decarboxylation procedure is generally carried out within the preparation of the starting material or botanical raw material (BRM), prior to the initiation of the extraction process.
They then go on to perform a few experiments to determine the most efficient temperature and length of time to cook it for. This is a little tricky for THC because the heat used to convert THCA will also degrade already present THC into CBN.
Quote:
The heating was performed in an oven with forced air circulation.
Their conclusion:
Quote:
Therefore laboratory studies demonstrate the optimum conditions for the decarboxylation of: Chemovar producing primarily THC to minimise CBN formation, is 1 to 2 hours at 105 C. or 1 hour at 120 C.
They go on to say that this is only the optimal conditions, and as the batch size increases, because of uneven heat transfer throughout the material, the temperatures and lengths of time would also need to be increased. They did this themselves when they prepared their own material with a batch size of 4 kg.
Quote:
Approximately 4 kg of milled BRM (either THCA or CBDA) to be decarboxylated was initially heated to 105 C. and held at this temperature for about 15 minutes to evaporate off any retained water and to allow uniform heating of the BRM. The batch was then further heated to 145 C. and held at this temperature for 45 minutes to allow decarboxylation to be completed to greater than 95% efficiency.
Alrighty, now that everything has been prepared, we can actually start the extraction!
Quote:
Preferred conditions for liquid CO2 extraction are as follows: Decarboxylated botanical raw material is packed into a single column and exposed to liquid CO2 under pressure.
Batch size: Approximately 60 kg
Pressure: 60 bar. +/-.10 bar
Temperature: 10 C.. +/-.5 C.
Time: Approximately 8 hours
CO2 mass flow 1250 kg/hr . +/-.20%.

Preferred process parameters for production of BDS are: extraction time >10 hours, CO2 pressure 50-70 bar, extraction temp 5-15 C., CO2 mass 167 kg/kg BRM.

Following depressurisation and venting off of the CO2 the crude BDS extract is collected into sealed vessels. The original BRM reduces to approximately 10% w/w of crude BDS extract. The crude BDS extract is held at -20 C.. +/-.5 C.
That step basically uses the CO2 as a solvent to extract all the cannabinoids it can out of the plant material. It also gets a few other things, so the product is then further refined.

Quote:
The second stage in the manufacturing process is Extraction No. 2, referred to as "winterisation" using ethanol.
...
It was found by warming the crude BDS extract to approximately 40 C. the mixing ability of the crude extract with solvent was improved.

It was preferred to chill the "winterisation" solution to -20 C. for about 48 hours.

Preferred process parameters for production of BDS are: extraction temp 36-44 C., ratio ethanol/product approx. 2:1, freezer temp -25 C. to -15 C., time 48-54 hours.
...
The ethanolic solution produced in the second extraction stage requires filtration to remove the resulting precipitation.

Filter size is preferably 20 μm.

Preferred process parameters for production of BDS are: total filtration time >6 hours.
...
The final stage of the manufacturing process is the removal of ethanol and any water that may be present.

Preferably this is carried out by heating at 60 C.. -.2 C. to give a vapour temperature of 40 C.. -.2 C. under a vacuum of 172 mbar. -.4 mbar. The distillation under these conditions continues until there islittle or no visible condensate. Reducing the vacuum further, in stages, down to approximately 50 mbar, completes water removal. On completion the BDS is transferred into sealed stainless steel containers and stored in a freezer at -20 C.. -.5 C. Preferred process parameters for production of BDS are: evaporation vapour temperature 38 42 C., vacuum pressure removal of ethanol 167 177 mbar, vacuum pressure removal of water 70 75 mbar 62 58 mbar 52 48 mbar, time <8hours.
What we are left with is the hash oil, with the following characteristics:
Quote:
The THC BDS is a brown, viscous, semi-solid extract consisting of at least 60% cannabinoids constituents. The cannabinoid constituents include at least 90% THC, about 1.5% CBD with the remainder being made up of other minor cannabinoids.
They take this one step further, though, and filter it through activated carbon to increase the shelf life of the THC, and to inhibit the degradation of THC into CBN.
Quote:
Results from stability studies on THC formulations indicate that THC in the form of BDS is unstable even at storage temperatures as low as 5 C.
...
The applicant has determined that a charcoal clean-up step may be conveniently carried out in close conjunction with the "winterisation" process by passing the ethanolic winterisation solution through a filter bed to remove precipitated waxes and then directly through a charcoal column in a single step and that the use of activated charcoal significantly improves shelf life.
...
Comparison of the levels of degradation reached after 12 months at 40 C. for the std BDS and the corresponding charcoal purified BDS indicate that for both the THC and the CBD extracts the charcoal purification increases the resistance to thermal degradation by over 50%.
And at the very end, they perform an experiment that basically goes against their method above, and adds 2% ethanol to the liquid carbon dioxide used in the first extraction, and then uses super critical instead of sub critrical pressures. They found that this is actually the most efficient method of extracting the cannabinoids:
Quote:
Thus, extraction of cannabis plant material with supercritical CO2 2% w/w ethanol provides an increase in recovery of the target active with no attendant penalty of loss of selectivity.

In Summary:

1. A switch from sub-critical to super-critical conditions produces little advantage in terms of overall recovery of cannabinoid from the raw material but does result in the disadvantage of reducing the active content of the extract.

2. The addition of 2% absolute ethanol modifier to supercritical CO2 results in a significant improvement in the recovery of cannabinoid from the raw material with no penalty of dilution of active content by co-extracted material.

And in closing, as a summary of the whole process:
Quote:
In a preferred embodiment the method of the invention will comprise the following steps, preferably carried out in the stated order starting from cannabis plant material: i) decarboxylation, ii) extraction with liquid CO2, to produce a crude botanical drug substance, iii) precipitation with C1 C5 alcohol to reduce the proportion of non-target materials, iv) filtration to remove the precipitate, v) evaporation to remove C1 C5 alcohol and water, to produce a final botanical drug substance(BDS).

A step of treatment with activated charcoal may be included between step iv) and step v), resulting in improved stability of the final BDS.
I'm glad someone else footed the bill for finding out this information, I'm sure it was incredibly expensive!

Last edited by BobbyDigital; 02-26-2010 at 03:41 AM. Reason: grammar
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