THC is excreted by capitate-stalked glandular trichomes, present on the epidermis (skin) of the plant, which release the plant resins to protect the plant from UV and predators, insects etc. If you look at a mature bud under a 20-30x magnifying lens you see slithers of long ice like crystals often refracting colour.
One of the best known hashish is the Moroccan double zero or 00. A friend from Holland once described the preparation of the 00. The small plants chosen (not a native strain to Morocco I’m led to believe) are the best and are shaken only twice (hence the 00) and what falls from these is classed as premium 00 hash. Subsequent shakes are the lower grades. During the early eighties and before, Amsterdam saw most of its hash sourced outside of the country, and although importation was illegal and punishable with a prison term, it was then, and undoubtedly still is big business. Often commercial traffickers would give the buyer a bonus by way of some 00 hash. I believe it is still held in high regards today. The hash was described as off white in colour
Getting back to your question, if you had the absolute best shake, say 00 quality, then the amount of THC present is still only a percentage of the powder, shake, whatever, although it may be as high as 20%. Why? The resin droplets also contain other compounds, some psychoactive, some not. As the biochemical pathways to THC are fairly well understood, it is easy to see why and what else is likely to be in there. The pathways themselves do get rather complicated, but it can be seen that compounds one or two steps away from THC are very close chemically to THC. These includes the precursors CBDs and the catabolic products, the CBNs etc., compounds with less or no psychoactive properties, but present in different amounts dependant upon variables such as strain, growing conditions etc. and the age of the plant.
So you don’t have solely THC, but a mixture of plant resins including THC, CBN CBD, chlorophyll and heaps of other plant tissues and constituents.
The next question usually raised is how can the THC be purified to crystals?
What about fractional distillation under vacuum? Unfortunately this procedure won’t work as the boiling points of these substances are too close together. In a lab the chemist has access to equipment specifically designed to separate mixtures of compounds. Techniques such as HPLC (High Performance Liquid Chromatography) are employed, which use 2 mediums; a stationary a phase and a moving phase. These phases are carefully chosen to suit the substances desired to be separated. The basics of how this works are quite simple.
Firstly look at a simple chromatography setup. This form, known as Elution chromatography uses a burette filled with the stationary medium, say Aluminum oxide, and the mixture of compounds is dissolved in a suitable moving phase, say a mixture of cyclohexane and ethyl acetate (its amazing how many hours must have spent discovering and recording this stuff). The solution is poured into the burette and as the solution travels through the stationary phase, each component will be eluted at a different rate. The electrostatic charges and molecular polarities of the compounds means one will move at a faster or slower rate to the others. To hasten the process, air pressure may be applied to the top to push things through.
Although the above method works for many things, mixtures of several compounds or characteristically similar compounds may not separate, or be tediously slow. To identify your separated compounds, it is also necessary to do TLC (thin layer chromatography) which is also fiddly.
So HPLC was invented. These amazing devices can not only separate but analysis what each chemical is. A known high quality sample is used to reference the compound signature, and absolute separation is achieved between compounds. This is still a skill based operation however with a competent operator incredible things can be achieved.
Hope you got something out of it. Mmm...maybe I shouldn't get up so early...
[ 18 September 2002: Message edited by: phase_dancer ]