After reading this article you will understand why butane and propane are commonly used to make concentrates, why Cannabis lingers in the body, and why isopropanol can dissolve just about anything.
*Some of the more in depth chemistry information is presented in brackets in smaller font.
Extraction Is All About Polarity
The key to getting a good cannabinoid extraction lies in understanding how cannabinoids interact with other compounds. The terpenopholic compounds such as cannabinoids and terpenes, are basically oils. This is why cannabinoids blend so well with butter!
So, remember that oil and water do not mix. This is because of the polarity of these two different substances. Because oil is non-polar and water is polar, they repel each other and avoid mixing.
[Polarity refers to whether or not electrons are being shared equally or not among atoms in a molecule. Compounds with equal sharing of elections are considered nonpolar, where compounds with unequal sharing of electrons are considered nonpolar.]
BHO and PHO extract producers know this principle very well. The hydrocarbon based solvents used in these extractions are nonpolar, and so attract the nonpolar compounds in Cannabis while repeling polar compounds. As a result, oils like cannabinoids and terpenes are pulled out of the plant and carried to a reservoir.
It's well known that Cannabis metabolites linger in the body for days to weeks, leading to a lot of controversy over drug testing and “stoned driving.” The polarity of those compounds is also responsible for the controversies. Fat cells, or adipose tissues, are full of lipids, which are oily. Because of the presence of these nonpolar compounds, cannabinoids and other nonpolar compounds can slip right through and get stored in these fat cells.
In order to prepare samples for analysis, the Cannabis material must go through an extraction process in order to transfer cannabinoids out of the material and into some solvent. Since cannabinoids are nonpolar, alcohol is usually the solvent of choice. This is for multiple reasons.
Alcohols like methanol, ethanol, and propanol are pretty special compounds. This is because they contain both a part of the molecule which likes polar compounds, and there are parts of the molecule that like nonpolar compounds.
[What makes an alcohol an alcohol is the OH on the end of the molecule. This oxygen-hydrogen bond gives alcohols like methanol, ethanol, and propanol, a unique characterisitic. The OH group on the molecule is hydrophilic, meaning that it has an affinity for water and other polar compounds. The hydrocarbon group of the molecule, like the CH3 in methanol, is hydrophobic. It wants to have nothing to do with water and prefers nonpolar compounds. So because of these two groups of atoms that make up these simple alcohols, the alcohols can dissolve both polar and nonpolar compounds!]
Using alcohols is nothing new to the Cannabis industry. Tincture manufacturers often use alcohol as a method of extracting cannabinoids. The alcohol is then allowed to evaporate off so that the solution is more concentrated.
Alcohols are also used as solvents because it can be damaging to analysis equipment to inject solvents that are more complex or of fixed polarities. They can leave residues and clog up the machine.
There are a lot of nuances and calculations that go into figuring out best methods for extractions, but the basic method for extraction is the same. A solvent is used to collect the nonpolar compounds of Cannabis, which includes the cannabinoids. Then these mixtures are prepared for whatever analysis method is being used, such as Gas Chromatography or High Performance Liquid Chromatography.
Potency testing for edibles is a totally different story because various sugars, fats, and waxes are contained in the material which must be filtered out before being injected into an analysis machine. Another article will detail the complexities of Cannabis edible testing.
For now I hope this provided some technical insight into the chemical workings of Cannabis potency testing. To learn more about Cannabis compounds or testing, visit www.kenevirresearch.com
Jason Wilson M.S.
Taking the guesswork out of Cannabis