This hemp trim did not age well in Jason Reposa’s garage, and readers guessed about the extent of Total CBD loss…

The years aren’t kind to cannabis flower. Over long periods of time, it dries out, and terpenes evaporate. Microorganisms have time to proliferate, and reactions with oxygen degrade flavor and potency.

It caught our attention when Jason Reposa posted about old bags of hemp trim in his garage. This is an opportunity to observe aging first-hand!

The quiz was more like a guessing game than a test of science acumen, so don’t feel bad if you didn’t get it. We also made the quiz pretty tricky, but readers did nicely.

I had thought to actually try smoking some of this, but one sniff told me no way! It has that nasty brick weed smell I hoped to never experience again. I note that, in addition to the temperature (MA sometimes sees temperatures above 30 °C), the bag containing this hemp was not truly air-tight. Oxygen diffuses through plastic bags at rates that become significant over years of storage. This hemp looked brownish and smelled stale.

A reliable report about the chemistry of aging cannabis is accessible on the internet here. https://lnkd.in/dAVsJwJe

It reports that at “Room Temperature,” a steady rate of loss was established; Total THC diminished by about 8% of the original value per year, with faster loss in year one. In particular, cannabis lost 34.5% ±7.6 of THC potency after three years’ storage.

We suppose the climate in Jason’s garage differs from mid-1990’s room temperature in Mississippi. We’re also comparing experimental degradation of CBD to a paper about THC.

Four measurements found Jason Reposa’s hemp trim at 8.3±0.4% CBD, 2.8±0.2% CBDA, for ~ 10.8% Total CBD. Our findings are consistent with El Sohly; this hemp was “about 15%” Total CBD to start with, and three years storage diminished potency by about 1/3, to “around 10%.”

At first, I was surprised that hashtag#LighLab found no CBN. Isn’t that one of the products of cannabinoid degradation? I read El Sohly’s paper again, and realized that the efficiency of converting THC to CBN was reported to be on the order of 13-20%; in other words, losing 5 wt% of THC would give, at most, only 1 wt% CBN.

hashtag#Lightlab’s limit of quantification for CBN is 0.47 to 0.71 wt%, depending upon the mode (I tried several). So, even if CBN formed from CBD at a rate similar to that of THC (a big if), we might well miss it with this machine, which isn’t sensitive enough.

Limitations: One sample, no measure of exposure, no original COA for precise package of material studied here, no control, I never even saw Jason’s garage!!!!