You need a gas chromatograph and an analyzer probe. The whole setup will cost you about 8-9k. I actually have one, its an HP 5890 II GC dual, with an FID. Ive used it to test cyclic terpenes and thc before. its not as easy as you think, and you need knowledge of how the machines work unless u want to chuck down 21k for the complete automatic ones. I would NOT recommend buying one unless you have worked in a lab before.
Props to owning one of those
and posting on this site. You probably have a pretty cool job (or hobby).
Okay, so I just googled this thread and have to bump it. I majored in Chemistry and Chemical Engineering in college, and have good knowledge (and practice) of analytical chemistry techniques. I am not convinced that you need a GC or FID to test the percentage of THC in bud (or more specifically, solution). At least not for the precision I'm looking for. I'd only want comparative measurements.
The reason I'm even looking for this information is because I'm interested in finding good solvent extraction techniques, specifically different types of fatty acids (oils) and sugar alcohols like glycerin. So a good scientist needs a comparative quantification of how much THC is dissolved in the solution.
I'm thinking the best choice is UV-Vis spectroscopy. A lab instrument would still be prohibitively expensive, I agree, but luckily we all already have very good light radiation detectors: our eyes! I've seen on TV that sometimes when they catch a smuggler or someone with lots of plant material, they test it with a field kit that turns a different color to make sure it actually has THC and isn't, say, a mistaken hops dealer selling to friendly homebrewers. From what I've seen on TV, it reacts with THC and turns blue. They grind up a little of the bud, drop a solution containing this chemical in it, and if it turns blue it has THC. I assume that the more THC, the more of this blue product is produced. That seems like enough for me.
Tell me if my logic isn't sound, but couldn't you:
1) extract equiv mass of bud in set volume of each of the oils
2) dilute samples with a clear solvent to bigger equiv volumes, to a point where all the solutions were fairly clear (as opposed to green, or wtv color a negative blank would be) to your eyes to prevent "noise"
3) drop equiv amount of this dye solution in it
4) rearrange the translucent containers from darkest to lightest (highest to lowest), as seen to your eye from the same vantage point with the same light source. I figure some may be very close, but you have the freedom to experiment with light sources and angles. I think I even have a glass prism I could use as a diffraction grating... And mark different spots against the wall and bust out a calculator, if I chose (or was forced) to be rigorous.
I found on google that this chemical is known as "Fast Blue B" (
http://www.ncbi.nlm.nih.gov/pubmed/480177)- it's $63 for 10 g (which is way too much mass for this, but a whole lot cheaper than a GC setup) but it's backordered on Sigma-Aldrich, and I don't think they or any chemical or biotech company ships to residential addresses (and I don't blame them!). It also seems that the field kit (packed columns with this stuff on the media) is not for sale to normal, non-cop people.
Perhaps the chemist I quoted, or one of the other chemists/smart people on this thread, can think of a solution (no pun intended)?? Is there a way for people to get non-sketchy, non-regulated, but specialty chemicals like this? To be used for good science, not as precursors for consumption, like all the meth-head idiots that ruined chemistry for all non-professional chemists! I think this is the answer to the original poster's, and my, question. (Adding that to compare flower buds you would just vary the "strain" of the buds in step 1 instead of varying the solvent - maybe someday I'll tell you the best one, haha. If you had numbers and good optic knowledge of prism measurements, you could divide by the mass of bud you use, you would get what
I would call "% THC", although it would truly only be a reduced variable and empirically good for other measurements taken using the same technique... OR you just keep "standards" - in your fridge? - of solutions you thought were "really weak", "average", and "exceptionally strong")
Thanks for any advice