I’ll bet if you’re in the hemp industry, you’re confused at the lack of regulations on contaminants in biomass and downstream products, and even more befuddled by the Farm Bill Interim Final Rule, which seems to interchangeably use delta-9-tetrahydrocannabinol (THC) and total THC, which is calculated using the formula [(THCA * 0.877) + THC]. Given that the document discusses using gas or liquid chromatography (GC and LC, respectively) to quantify THC, it’s clear that the number sought is total THC, since THCA (tetrahydrocannabinolic acid) decarboxylates to THC in a GC, anyway.
Hemp farmers are expected to evaluate their biomass to confirm that they’re cultivating industrial hemp and not cannabis, as per the < 0.3% THC requirements for hemp. Much of the hemp being grown, however, has begun to take on the organoleptic properties of cannabis cultivars from a glut of resin and terpenes. These plants aren’t grown for their fiber, and therefore, it’s even more important for farmers to be cognizant of where their plants stand regarding THC potency.
Sending samples to a 3rd party lab is vital, but how likely does a few grams analyzed relate to the acres being harvested? The other concern regards sampling. How do you nominate what to send to the lab? Do you pull a couple of flowers from the stalk of one plant? Or do you pull flowers from multiple plants, and pool them? The right answer depends on what your intentions are regarding final product. Will it be smokable hemp? If yes, sending flower to the lab would be adequate.
If you’re planning to send biomass to an extraction facility, however, you’re likely not just sending trimmed hemp flowers, but rather more complete plant matter including leaves and stems. Any sample sent to the lab should reflect what biomass you’re planning to have processed such that there aren’t surprises.
Hemp farmers needn’t just rely on 3rd party testing, however. Some instrument manufacturers have targeted those outside of the analytical lab. To date, there have been two main avenues pursued for in-house testing: chromatography and spectroscopy. The former is a primary measurement technique, meaning you get data straight from that instrument. You measure a sample and get a potency. That output comes from first analyzing multiple concentrations of cannabinoid standards and building a calibration curve, described by a straight line and an equation. The signal generated from unknown samples is plugged into the equation, generating the potency.
Spectroscopy relies on those primary techniques, too. Instead of measuring standards, however, cannabis or hemp samples are measured. A plot similar in appearance to a chromatogram is generated (the spectrum), which is the molecular fingerprint of the sample. This data is coupled to chromatographic potency data, so rather than calibrating to standards, you’re calibrating to chromatography data. This creates a data model.
Data models aren’t one size fits all. There are integral concepts to consider when selecting instrumentation. How do you know it’s working, for example, if you can’t measure standards? How low can you measure? Most importantly, how accurate is the technique? In the conclusion of this article, the capabilities and limitations of these analytical methods will be introduced.
Image Credit: Inquirer