Home-brew Cannabis potency analysis

Last year, due to an issue with improperly-marked marijuana plants, we ended up with some plants that had zero CBD content.  We are interested in the pain management properties of CBD, not getting high, so last year was a waste of our gardening time, water and garden space.  It was when I started looking into ways of doing my own analysis.  Sending material to a lab is expensive, particularly if you want to test a number of times to optimize your THC/CBD ratio (which depends on the "ripeness" of the buds).  My results, if successful, also could be helpful to others who are depending on getting the right "stuff" for their needs.

I started by looking at current mainstream methods.  Mainstream analysis techniques fall into several categories:  Gas chromatography, liquid chromatography, mass spectroscopy, and IR spectroscopy.  Thin Layer Chromatography kits can be purchased for home use, but they're not very good for quantitative work -- the size of a particular colored blob on the TLC plate is roughly proportional to the amount of chemical (THC, CBD etc.), but in my experience it was difficult to interpret the streaks on the plate.

While mulling over all these approaches, I did find a purely chemical way to at least tell you if your marijuana has some CBD in it.  It's pretty simple, too:  make up a 5% (by weight) solution of sodium hydroxide (A.K.A. lye) in ethanol or rubbing alcohol.    Put 100-200 milligrams of your decarbed bud in a glass vial and add the solution  at least halfway up the vial.  Screw on the cap and shake vigorously.  If the solution turns blue, your marijuana contains CBD.  The darker the color, the more CBD you've got.  THC doesn't turn blue.  With careful solution preparation and careful weighing it might be possible to get a quantitative measure of the CBD, but you'd need a spectrometer to tell you what the absorptivity of the solution is.  You can make a spectrometer using a web cam and DVD (for the diffraction grating).

I also discovered a paper that has a lot of information on cannabinoid analysis.  Its title:  "Chromatographic and Spectroscopic Data of Cannabinoids from Cannabis sativa L.", by Arno Hazekamp, Anja Peltenburg and Rob Verpoorte.  It turns out decarbed cannabinoids have a distinctive red fluorescence when illuminated by UV.  This may be the basis of a commercial THC analysis gadget that is currently selling for around $300 (pure speculation on my part).  The photo below shows three different samples I examined.  Two are decarbed bud and one is UN-decarbed.  Hexane is used as the solvent.

Pretty interesting.  While not shown, I also observed the same fluorescence in cannaoil made with coconut oil.  It glows a very pretty orange color, while pure coconut oil just reflects the purple color of the UV flashlight.  Cannaoil made with un-decarbed cannabis also doesn't glow orange.  The flashlight's peak output is specified to be at 390 nm.

The fact that the decarbed cannabinoids fluoresce suggests the mechanism is related to the site where the carboxyl group was (formerly) attached.  It's a benzene ring structure with an OH attached so technically speaking it's a phenol.  It would be nice if CBD fluoresced with a different color but at least the effect can be useful for a total cannabinoid test.

Searching the web, I found a thread on a MJ forum where the poster had noted the same thing.  The post mentioned some variability in the effect, comparing a commercial extract to a home-brew version.  I suspect the starting materials were different -- one was decarbed, the other, not.  There was speculation that the fluorescence was from chlorophyll, but as can be seen in my photo above, a chlorophyll-loaded UNdecarbed sample doesn't glow orange.  It's the vial on the right.

Spectrometer -- Useful for CBD/THC analysis?

The top spectrum shows the result for a high THC strain and the bottom shows the result for a high CBD strain.  A calibration procedure was used to compensate for variations in the illumination source (a 100 watt quartz-halogen lamp).  The color differences (as seen by eye) are mostly explained by the slight shift in the peaks centered around 625 nanometers -- the CBD color peak is slightly redder.

Conclusion:  I got a nice spectrometer to play with, but the idea of using Fast Blue B dye as a way to distinguish THC from CBD didn't work out.

Home-brew Spectrometer

Due to a quality control problem at a local marijuana dispensary, we found the high-CBD plants we thought we had actually were unknowns.  This became apparent when the plants got big enough to exhibit their typical growth habit and odor (smell can vary widely among different clone types).  To make it clear:  we want high CBD for pain management.  Not interested in getting high.

Via online searching I found a chemical test for CBD and it showed that just one of the 3 clones contained much CBD -- but, unfortunately, the test is not very quantitative.  It relies on the development of a purple color when the plant material is added to a 5% solution of sodium hydroxide dissolved in alcohol.   The darker the color, the more CBD is present.  But eyeballing is not very accurate.  I started thinking that a spectrometer might improve the accuracy of the test.  In addition to the alcohol-hydroxide test, there is a very sensitive test that will stain THC and CBD slightly different colors.  It is a dye called Fast Blue B, dissolved in water, and is used to develop thin layer chromatography (TLC) plates.  So it MIGHT be possible to determine the ratio of THC and CBD by using Fast Blue B and a spectrometer to resolve the different colors.

But commercial spectrometers are expensive.  Sure, it is possible to find them for less money on Ebay:  but often they need software and a computer, and if the package is complete the price goes up.  The other aspect of this work is to hopefully make it possible for others to do the same measurements on their own material, so a one-off purchase from ebay won't cut it.   As an alternative I found an open-source spectrometer here.  Cost is around $50.  For that you get a web cam, an optical slit, a CD-R disk (to turn into a diffraction grating), a black cardboard box and materials to assemble it all.  I put the thing together and found it wasn't mechanically stable enough to generate repeatable absorption spectrograms.  So I used the essential parts -- the camera and slit -- and built my own spectrometer.  The photos below show the spectrometer I put together.

Exterior showing the slit and lid.  The "hinge" is a length of adhesive-backed aluminum (which is opaque to light).

This is a photo showing the "optical holder" design.  It is a block of oak with a flat-bottomed hole just large and deep enough to glue in a super magnet.  The bottom of the spectrometer is a steel plate, so the blocks stay put -- but are easy to move around to optimize the optical path.

And here is a photo of the interior.  The diffraction grating is glued to one of the optical blocks.  I sawed a slit in the block to provide a robust mounting point for the grating.  The web cam is attached to an optical block using heavy-duty double-sticky tape.  The corners of the enclosure are reinforced with wood blocks that were glued in place.  The top, sides, and ends of the box are made using foam-core poster board.  Black, of course.  I also put a length of the poster board on the bottom, to reduce reflections that would degrade contrast of the spectrum.  I had some black silicone caulk so I ran a bead along the front corners and along the bottom edges as well, to reduce light leaks.

And here is the spectrum of a CFL lamp, obtained using my spectrometer:

Unfortunately, I found the web camera is not compatible with the Public Labs spectrometer software.  At least, not on my linux laptop.  So I found it necessary to write my own program(s) to do the job.  I found a starting point here but it has a fairly serious memory management problem -- it acquires a bunch of frames, and only then performes averaging.  I modified the code to acquire one video frame, then extract ONE line of interest for processing.  This way I can average over any number of frames without running out of memory.  I also wrote a version to get the calibration factors needed to convert pixel positions to wavelengths.  The end result is a system that easily resolves the two green emission lines around 540 nanometers, and has a low noise level in the data.

Now I can move on to testing my THC/CBD measurement idea....

Update

A lot has happened since my last post.  Some highlights:

I have a new hip joint.  The joint on my right side was bone-on-bone, painful enough to restrict my activities.  The surgery went quite well -- I was out of hospital the same day of the procedure!  And right now I'm pretty much back to normal as far as muscle strength in that leg.

Another interesting project:  our old barn.  Two winters ago we had a fairly heavy snow fall, and the weight was enough to cause one of the walls to buckle.  Not much of a foundation, especially after many years of dry rot.  Fortunately the wall just dropped a few feet before finding a new equilibrium, and the rest of the barn was flexible enough to not shatter.  It just looks pretty bent.  I am in the process of rebuilding the wall.  I am jacking up that side using some harbor freight "farm jacks".  The temporary support header is several feet over from the old wall, so, once the barn is back to square (more or less) I will install new concrete footers and a new wall.  I will post some photos when I have a chance.

The garden is our perennial summer project, and like previous summers it took a lot of time.  I'm just glad I was in good enough condition so we could get the garden in.  We did have some help putting in some things, like the cucumber and bean trellises -- thanks to Mike and Debbie for that!  However, I wasn't quite in good enough shape to mulch the garden like I usually do, and we paid the price -- weeds galore.  And perhaps that is why our peppers and tomatoes didn't do as well this year as previous years.  Even so, we got enough tomatoes to put up 40 pounds of tomato-vegetable juice and 20 pounds of pasta sauce.

Another milestone:  we initiated a quarterly "draw" from our investments, to cover expenses.  Up to that point we were funding our expenses from savings in the bank accounts.  I have tracked our burn rate so had a pretty good idea on what we would need on a quarterly basis.

Garden Goodies

Here are a couple of photos showing some of our garden produce.

The top photo is a bowl-full of Aji Limon peppers.  They are spicy with a fair amount of "sneaker heat", and, in addition to the yellow color, they actually do have a nice citrus-like flavor.  I turned these into a fermented brined-pepper mash.  Very tasty, and a good way to preserve garden produce for the winter.

The second photo shows the winter squash we got this year.  There are several varieties shown here:  Cinderella pumpkin (the large orange guys), Kuru (small orange), Buttercup (small dark green), Sweet Meat (medium-sized gray-green), Butternut (oblong tan fruits), and Queensland Blue (medium sized gray-green, ribbed).  The Kuru and Queensland Blue were new to us this year.  We like the Kuru -- we put it in a batch of Mussaman Curry last night.  The Queensland Blue is very hard and dense, but the flavor is not as good as the others.  Our overall favorite winter squash:  Sweet Meat.  Best keeper:  Butternut.

Rocking Toy Part 2

Summer activities -- gardening, playing, etc. have delayed part 2 of my rocking toy post.  We're canning tomato juice right now, which involves some basic hanging around to do the hot water bath -- so I have some "spare" time to do part 2.

In part 1 I explained the basic principle of a pendulum or other simple mechanical oscillators.  My first photo shows the can opener that first got my attention:

 It's a simple old-fashioned "church key" with a punch on one end and a crown cap remover on the other.  In the context of a rocking toy, the opener rocks on the point of the punch and the arc of the cap remover.

 The above photo shows the church key with some added weights -- a stack of small neodymium magnets.  The idea was to raise the overall center of gravity so it was closer to the center of rotation.  This in turn would reduce the oscillation frequency, which it did -- the new oscillation frequency was about 1 hertz.

And now, my version of the rocking toy.  The main piece is about the same length.  I drilled and tapped a hole on the left for the pivot, which is a bolt whose end was formed into a taper using my lathe.  The right side has an arc machined into it, using my milling machine and rotary table.  I smoothed the arc with some 220 grit wet/dry sandpaper.  I also needed to bend the right-hand end down, to replicate the church key.  To make sure the bend was exactly perpendicular to the long axis of the bar, I cut a slot (again, with my mill) from the top to bottom of the bar.  It is about halfway through the bar.  Then I put it in a vise and bent it until it was about the same angle as the church key.

The end result is a mechanical oscillator that, again, has a surprisingly low frequency -- although for some reason as yet undetermined, my version oscillates at a slightly higher frequency.  Anyway, it is a fun "twiddler" to play around with.

If I was going to make another one, I would use cold-rolled steel instead -- it has a much nicer finish.  And refine the corners on the left side so it has a more refined appearance.  But those are just aesthetics.

First food post

Something that should be clear by now is we have a broad range of interests.  That includes food.  My wife and I have a 1600 square foot vegetable garden.  In some years we have extracted about 1,000 pounds of winter squash from it, in addition to quarts of tomato sauce, myriad zucchini, peppers, cucumbers, leaf vegetables, beets, basil, and on and on.

But we've been aging cheese, as well.  A well-aged Tillamook cheddar can  beat just about any other cheese, and, if you have the space in your 'fridge (or a separate refrigerated cheese vault), you can enjoy some really flavorful cheese for a very cost.  We have aged cheddar, in its original wrapper, for well over 10 years.   The acid level of the cheese, plus the salt content, does a good job of preserving it.  And the aging process produces lots of flavor components (like glutemates) that really ratchet up the flavor.

As an experiment, we bought a 2 pound brick of Tillamook "colby" cheese awhile back.  It is a milder sorta-cheddar/jack cheese.  But the price was right, and we had the space to store it awhile.  Well, that aging time turned into 15 years (!).  We rediscovered it, observed some potential issues, so decided to open the package and taste it.  Well, it is just fine -- some might say terrific.  Because this style of cheese often has some added red pigment, it looks a little odd --pink-- but it tastes great.  By the way, a well-aged Tillamook that has absorbed some truffle flavor from some Oregon white truffles, is amazing.

The main issue with preserved food is either the hydration level (think jerkey on the good side) or acid.  If the acid level produces a pH level of 4.3 or lower, clostridium botuliun can't grow, so the food is safe to consume.  Not to say it's tasty, that depends on other fermentation parameters.  Fermentation is not just about beer or wine, it helps make sauerkraut, kimchi, pickles, and artisan sausages.  It converts part of the food product to (typically) lactic acid.  Acids reduce the pH of food, and most putrefying bacteria don't like low pH.  So they are more stable.

Fermentations like this are used to produce (as mentioned above), sauerkraut, pickles, kimchi and sausages.  It also is used to make bread, cider vinegar, wine, beer, sake, miso, soy sauce, fish sauce, and many other foods found across the world.  In most cases, the fermented foods have more nutritional benefits than the original input biomass.  This it not an opinion.  Additional nutritional benefits are well documented.

Just say'in.