03.2020 | THE SCIENTIST 53derived products falls to states, creating
a patchwork of different testing require-
ments across the country. In addition,
state governments issue little to no guid-
ance about protocols for testing products
for either potency or safety. Instead, labs
have had to trailblaze the development of
their own methods.
Now, in a cannabis testing industry
that is only a few years old, it’s evident that
reports on potency can vary from lab to
lab, and recalls of contaminated products
happen across the country, threatening
consumer trust. “It’s not really at all like
any other industry I’ve worked in, in that
they’re still trying to work out proficiency
and certification standards,” notes Frank
Conrad, an analytical chemist formerly in
the biofuels industry who now runs Colo-
rado Green Lab, a consultancy firm for the
cannabis industry.
The strength of pot
Knowing the concentration of active
ingredients is crucial throughout the can-
nabis supply chain. Cultivators and retail-
ers want to know a product’s strength
because higher concentrations of CBD or
THC (the more psychoactive compound
of the two) usually mean higher prices.
Potency information is also important for
doctors who prescribe cannabis to their
patients and for recreational users who
wish to control the intensity of their high.
Labs are tasked with testing samples at
every stage of production—from the
whole plant to the manufactured prod-
uct, and often its final packaged form.
In the absence of federal guidance,
labs have had to develop and validate
their own methods of measuring the
concentrations of THC and CBD, and
distinguishing between them—a partic-
ular challenge due to the molecular sim-
ilarity of these two compounds to each
other and to other cannabis compounds.
Many labs have converged on a few ana-
lytical techniques, although the precise
details of each company’s procedure are
often proprietary. Hudalla, who runs the
Massachusetts-based cannabis testing
lab ProVerde Laboratories, says he reck-
ons that most use high-performance liq-uid chromatography (HPLC) to measure
concentrations of THC and CBD, plus
their acidic precursors, tetrahydrocan-
nabinolic acid and cannabidiolic acid,
which degrade to THC and CBD upon
being heated through smoking or prepa-
ration for oil and edible products.
After the dried plant has been ground
up and doused in a solvent to extract can-
nabinoids, the residual fluid is fed into a
HPLC system which separates different
compounds by using pressure to force
the mixture through a granular material.
The technique is based on the principle
that molecules with different structures
take different amounts of time to pass
through this material. If done correctly,
the method allows chemists to separate
THC or CBD from terpenes, flavonoids,
and other cannabinoids and to detect
each compound’s concentration.However, there are many accounts of
labs producing starkly different potency
measurements for the same products—
some results varying by as much as 40 per-
cent, according to a 2018 report by Mar-
ijuana Business Daily. Retailer Jerred
Kiloh, who owns a marijuana dispensary
in Los Angeles, has himself received very
different estimates from different labs
testing the same products. “That’s what
we deal with constantly,” he says.
Many experts blame this variability
on the lack of standardized methods for
determining marijuana potency. Lab pro-
tocols can differ in the specific solvents
or reagents used during extraction and
analysis. Then there are the instruments
themselves, which may come from dif-
ferent manufacturers and have different
calibration standards, potentially contrib-
uting additional variation.
Complicating matters further is the
variety of cannabis products on the mar-ket, some of which are easier to analyze
than others. From CBD-containing tinc-
tures, lotions, and dog treats to THC-
infused chocolate bars and turkey pot
pie, each product needs to undergo a
custom cannabinoid extraction method
before its ingredients can be tested. Data
from California’s Bureau of Cannabis
Control suggest that the more complex
the product, the more likely it is to be
inaccurately labeled. In 2018, regula-
tors found that 10.6 percent of cannabis
flower samples, 20.4 percent of inhal-
able oils and waxes, and 32.9 percent
of edibles, tinctures, and lotions carried
labels with potency estimates that were
more than 10 percent different from the
true value.
Antonio Frazier, vice president of
operations at California-based testing
company CannaSafe, worries that these
inaccuracies—and the recalls that often
follow—make consumers wary of the
industry. “People have a hard time trust-
ing us,” he says.A safety issue
The stakes are higher for contaminant
testing than for potency testing, as weed
contaminated during cultivation, pro-
cessing, or packaging could be dangerous,
especially for frail or immunocompro-
mised patients. For growers, this sort of
safety testing can be “make or break,” says
Frazier. A finding of contamination could
force them to discard entire batches worth
hundreds of thousands of dollars or more.
Luckily for testing companies and
consumers alike, safety testing is in prin-
ciple more straightforward than potency
evaluation because labs can turn to meth-
ods prescribed by federal agencies for
testing other botanical products. Labs
often isolate pesticides using liquid chro-
matography and then assess their concen-
trations using mass spectrometry, a tech-
nique suited to detecting the often tiny
traces of contaminants. Techniques such
as PCR and DNA sequencing are used to
look for biological contaminants such as
fungi and bacteria.
A more significant obstacle in cannabis
safety testing is uncertainty about what con-Why would marijuana, espe-
cially as it’s being considered
medical—why would that not
be tested?
—Christopher Hudalla, ProVerde Laboratories