My Restek colleagues Julie Kowalski, Michelle Misselwitz, and Amanda Rigdon, along with Professor Frank Dorman from The Pennsylvania State University (PSU), report here what we believe is the first QuEChERS extraction of marijuana, with subsequent analysis using GCxGC-TOFMS. We were assisted in this task by Randy Hoffman, a Police Officer Specialist/Evidence Technician at PSU, who very kindly donated the samples confiscated from some students who probably should have had their minds on class, not grass.
Our interest in this topic is mainly about medicine, since at least 15 states (Pennsylvania is not one of them) and Washington DC have enacted laws to legalize medical marijuana. When you fill your prescription, how do you know your remedy is active (potency, or cannabinoid content), pesticide-free, and without bacteria or mold or fungus? Well, you probably don’t, but eventually FDA might get involved and we’ll need good, robust analytical methods, especially for pesticide analysis. We think that you might be able to do one extraction for both potency and pesticide determinations and we’re high on QuEChERS, so we went for it.
First, the potency work, or cannabinoids determination. Although you don’t need GCxGC for the BIG THREE (cannabidiol, Δ9-THC, cannabinol; by the way, Restek has a reference material containing these compounds…), we used it to illustrate one of the benefits of that technique, the structured chromatogram. In the first figure below, the GCxGC contour plot (or chromatogram), you can see that compound classes position themselves in certain areas. This helps identification, and makes discovery of new compounds within classes a bit easier (e.g. perhaps there are undiscovered cannabinoids out there with medicinal benefits). Zooming in, we can see the terpenoid classes, which are thought to have therapeutic effects. Finally, you can see the cannabinoids, including cannabidiol, one of much interest given that “it has been shown to relieve convulsion, inflammation, anxiety, and nausea, as well as inhibit cancer cell growth” (http://en.wikipedia.org/wiki/Cannabidiol).
We quantified cannabidiol (CBD), Δ9-THC (THC), and cannabinol (CBN) for 4 marijuana samples using QuEChERS and GCxGC-TOFMS and the results are presented in the table below. Since the samples had been stored in an evidence locker for over a year in some cases, the CBN content is relatively high versus fresh marijuana. CBN increases as THC degrades. The THC content is in line with what is typically reported for higher grade illicit marijuana.
Stay tuned for a report on pesticide analysis of marijuana using QuEChERS and GCxGC-TOFMS. As you might imagine, the extracts are extremely complex, similar to what we saw in our dietary supplements work.