Written by Rich Press
THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY (NIST) has launched a program to help laboratories
accurately measure THC and other compounds in cannabis products, including hemp
and marijuana. The program aims to increase accuracy in product labeling and
help forensic laboratories distinguish between hemp, which is legal in all
states, and marijuana, which is not.
The Cannabis Quality
Assurance Program (CannaQAP)
is an interlaboratory study that will involve several exercises. In the first
exercise, NIST will send hemp oil samples to participating labs, which will
then measure the concentration of various compounds and report back to NIST.
Future exercises will involve plant material, edibles, and other samples with
Improvement Act of 2018, also called the 2018 Farm Bill, legalized any cannabis
material with a THC concentration below 0.3%. Below that number, it’s hemp. At
or above that number, it’s marijuana, and illegal in many states and by federal
law. A farmer’s crop can be destroyed based on that number, and interstate
shipments can be seized.
“But many labs have
limited experience making the type of quantitative measurement that the law now
requires,” said NIST research chemist Brent Wilson.
Before the 2018 law,
most crime labs determined if something was marijuana using the
Duquenois-Levine test, a preliminary colorimetric test that indicates whether
THC-like compounds are present, as well as a visual or microscopic analysis of
plant features. The presence of THC could also be confirmed using GC-MS.
However, while these tests indicate whether THC is present in the sample, they
do not provide quantitative results. The law now requires concentration
measurements and producing accurate and reliable numbers at levels as low as
0.3% can be a particular challenge.
Here’s how CannaQAP will
work. In the first round of exercises, NIST will send hemp oil samples—all with
the same, very carefully measured concentrations of THC, CBD, and 15 other
cannabinoid compounds—to participating labs. Those labs won’t be told the
concentrations of those compounds but will measure them and send their results
back to NIST, along with information about the methods they used to do the
responses, NIST will publish the measurements the labs obtained. That data will
be anonymized so that the names of the individual labs are not revealed.
However, the results will show how much variability there is between labs.
Also, NIST will publish the correct measurements, so each lab will be able to
see how accurate its measurements were and how it performed relative to its
“Anonymity means that
labs don’t have to worry about how their performance will be viewed,” said NIST
research chemist Melissa Phillips. “Our goal is to help labs improve, not to
call them out.”
The NIST researchers
will also assess whether some laboratory methods consistently produce better
results than others. If so, they can recommend that labs adopt the better-performing
Once that first round of
exercises is complete and the data is published, which could take from six
months to a year, NIST will run a second round of exercises. “We hope to see a
tightening of the numbers the second time around,” Wilson said.
NIST is also planning to
conduct future exercises with ground hemp and possibly marijuana, as well as edibles
and other types of samples with complex matrices. Some of these samples may
involve THC levels close to 0.3%, which will help labs determine the
reliability of their measurements near this cutoff value.
NIST is also working on
a hemp reference material—that is, a material that comes with known, accurate
measurement values. Labs will be able to use that material to validate their
measurement methods. One reason these measurements vary so much from lab to lab
is that, currently, there are no reference materials for cannabis.
“Labs can accurately
measure how much sugar is in your orange juice because they have standardized
methods and reference materials for that type of product,” said Susan Audino, a
chemistry consultant and science adviser to the Cannabis Analytical Science
Program of the AOAC International, a group that establishes standard methods
for laboratory analysis. “But cannabis has been a Schedule I drug since the
‘70s,” she said, referring to the Drug Enforcement Administration’s designation
for drugs that have the highest potential for abuse.
NIST produces thousands
of standard reference materials and has a long history of conducting quality assurance
programs for improving measurements. Past programs have helped labs accurately
measure compounds in dietary supplements, vitamins in human serum, and
environmental contaminants in groundwater.
“Our goal is to support
U.S. industries by helping labs achieve high-quality measurements,” Phillips
About the Author
Rich Press is science
writer and public affairs specialist with the National Institute
of Standards and Technology (NIST).