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CAL NORML: How Accurate is Cannabis Testing? Ring Test Assesses the Labs
by Dale Gieringer, Cal NORML ( dale [at] canorml.org )
Monday Sep 26th, 2011 6:09 AM
In the winter of 2010/11, California NORML and Project CBD initiated a “Ring Test” to assess the accuracy of the numerous analytical cannabis testing laboratories that have recently emerged to serve medical marijuana collectives, breeders, growers and patients.

Results of the study, which was coauthored by California NORML director Dale Gieringer and Dutch scientist Dr. Arno Hazekamp, are reported in the Autumn 2011 issue of O’Shaughnessy’s, the Journal of Cannabis in Clinical practice on pages 17-18, posted at: http://www.canorml.org/RingTestOShaughnessys_Aut11.pdf
How Accurate is Cannabis Testing? Ring Test Assesses the Labs


California NORML Release - Sep. 26, 2011


How Accurate Is Cannabis Potency Testing? California NORML and
Project CBD release the results of the first “Ring Test” to assess the
accuracy of analytical laboratories

Mixed findings show strengths and problems among analytic testing
services

In the winter of 2010/11, California NORML and Project CBD initiated a
“Ring Test” to assess the accuracy of the numerous analytical cannabis
testing laboratories that have recently emerged to serve medical
marijuana collectives, breeders, growers and patients.

Results of the study, which was coauthored by California NORML
director Dale Gieringer and Dutch scientist Dr. Arno Hazekamp, are
reported in the Autumn 2011 issue of O’Shaughnessy’s, the Journal of
Cannabis in Clinical practice on pages 17-18, posted at: http://www.canorml.org/RingTestOShaughnessys_Aut11.pdf

“We embarked on a parallel study of cannabis testing labs to shed
light on a significant, unresolved issue within the fledgling medical
marijuana industry in California and other states,” says Gieringer,
“We wanted to know how reliable is the information provided by
analytical cannabis labs? Are they adequately serving the needs of
medical marijuana patients and providers?”

Ten cannabis labs in two states agreed to participate in an
anonymous, side-by-side study to assess the accuracy and precision of
their collective work. The participating labs employed a variety of
analytical techniques and instrumentation to conduct their analysis.
Six samples drawn from the same sources were tested by each lab: four
herbal samples, including one CBD-rich strain, and two tinctures
(alcohol extracts).

Results of the Ring Test

- In most cases, lab results were consistent to within plus or
minus 20% on replicate samples (and often within 10%). For example, a
sample with 10% average THC content might range from 8% to 12% in
different tests. This is similar to the accuracy of the government's
potency testing program run by NIDA's lab in Mississippi, as well as
comparable government-regulated industries such as environmental
testing. Conclusion: The precision and proficiency of a majority of
cannabis testing labs compared favorably to other analytical testing
industries.

- While a majority of labs performed within acceptable limits,
some reported results that deviated substantially from the average,
with unacceptable deviations of more than 25% from the mean. Three
of the ten labs performed unacceptably on half of the tests.
Conclusion: Not all cannabis testing labs are performing up to par;
consumers are well advised to check the reputations and professional
experience of labs they work with, and to arrange backup tests from
more than one lab where accuracy is essential.

- Both gas chromatography (GC) and liquid chromatography (LC)
instrumentation yielded accurate results in testing of raw cannabis
samples, with comparable and acceptable repeatability for identical
samples. Conclusion: Both GC and LC instrumentation should be
considered reliable for cannabis potency analysis.

- In the case of the tinctures (alcohol extracts), there were
significant discrepancies in the results found by different labs, with
GC generally reporting significantly higher potencies than LC . This
made it impossible to reliably estimate the actual potency of the
original samples. Conclusion: More work is required to assess the
accuracy of current methods for testing cannabis tinctures, edibles
and other extracts.

- No analytical testing lab demonstrated precision that supports
reporting cannabinoid results to two decimal places. By unnecessarily
reporting results to the one-hundredth percentile, some labs created
an unrealistic illusion of precision that raises false expectations
regarding the degree to which accuracy is possible, given the 20%
variation observed. Conclusion: Labs should re-evaluate the precision
level at which results are reported.

The Project CBD / CA NORML Ring Test report is accompanied by a list
of ten questions that patents and providers might want to ask when
choosing to work with an analytical testing lab.

“Analytical labs provide an important service for the medical
marijuana community,” says Sarah Russo, Project CBD’s outreach
coordinator. “We hope that cannabis labs, while competing for market
share, will cooperate to improve their methods and maintain a high
performance standard. Medical marijuana patients and providers would
be well served by labs that share information and assist each other in
a collegial manner.”

For more information contact: Dale Gieringer at California NORML –
510-540-1066 dale [at] canorml.org or Project CBD – 707-581-1818, info [at] projectcbd.com

Release by: California NORML, 2261 Market St. #278A, SF, CA 94114
(415) 563-5858 - http://www.canorml.org
canorml [at] canorml.org