Cannabis testing is a crucial step in ensuring the safety and quality of cannabis products before they enter the retail market. Here, we take a step by step guided tour of a virtual cannabis lab and provide an overview of the journey of a cannabis sample from collection right through to the production of a certificate of analysis.
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s legal cannabis becomes available state-by-state in the US,
regulations surrounding the cultivation, processing, distribution, and sale are drafted and implemented
to provide traceability and security frameworks across the supply chain. Regulatory testing is the
gatekeeper to the markets, whereby representative samples of harvest or product batches are submitted to
certified labs and must pass a battery of public health-based criteria before being released for sale to
the consumer. These tests screen the representative test sample for a variety of constituents which
affect product quality and ultimately the end-user, lending legitimacy to product potency label claims
through issuance of a certificate of analysis (CoA) for every batch.
Harvest batches consist of
groups of plants grown together under the same conditions at time. The batch of raw plant material is
then harvested, trimmed, cured, and readied for distribution. A representative sample of the usable
product in its final form is provided to a certified lab for analysis before any of it can be released
for market shelves. A myriad of product batches can be derived from the raw plant material, including
concentrated oils and infused edibles, topicals, beverages, capsules, tablets, and other types. Similar
to a product lot in other industries, product batches are produced using the same processing parameters
and the same starting materials, at the same time, and assigned a unique batch identifier for the sake
of traceability and product integrity.
The following virtual tour will cover the typical
lifecycle of representative test samples once they are submitted to a certified laboratory for
regulatory testing.
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annabis laboratories are modern, tech-heavy facilities equipped with sensitive
analytical instrumentation and qualified, competent technicians and analysts trained for each type of
test conducted. Analysis often utilizes organic solvents like methanol and acetonitrile, or corrosive
liquids like nitric acid and hydrochloric acid. Therefore, chemical fume hoods are required to ensure
employee safety, along with safety glasses, gloves, and lab coats. Security is paramount at these
facilities, and all activity occurs in designated areas under video surveillance. When not being
handled, samples are retained in a secure storage location with restricted access to authorized
personnel only.
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pon request by the licensee, laboratory personnel are dispatched to the cultivation
or processing site to collect representative samples. The field samplers arrive on-site with fresh
personal protective equipment (PPE) including gloves, lab coat or coveralls, often hair coverings,
disposable bootie coverings, and surgical masks. Field sampling kits accompany the samplers, often as
carry-on sized hard-shell rolling cases, sanitized before each sampling site. A field balance is
verified with reference weights to ensure proper functionality and accuracy, and the sample increments
are randomly selected from the batch, weighed, and recorded on chain-of-custody (CoC) paperwork. Upon
completion of the sampling event, the representative samples with documented masses are relinquished by
the licensee’s signatory, and the field samplers assume custody of the product for secure transport to
the designated laboratory.
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pon arrival at the laboratory, samples are immediately examined to document
integrity. This intake process ensures the sample has not experienced tampering or adverse conditions
during transport. Typically, temperature minimum/maximum is documented by a device that travelled with
the samples, and sample packages are scrutinized to verify the tamper-evident seals have not been
broken, altered, or replaced, and no spillage, leakage, or other mishandling has occurred. Staff
accepting the samples verify that the recorded mass or number of units, and matrix type, exactly match
the CoC paperwork. Once samples are deemed acceptable, custody is transferred to the laboratory by
signature of the field sampler and sample acceptor. Samples are registered in the laboratory information
management system (LIMS), assigned a unique internal laboratory ID, and staged for visual inspection and
further sub-sample allocation to the various assays.
Visual inspection is specifically defined
by each state’s governing body, and often includes thresholds for debris such as dirt, cinders, hair,
insect parts, animal excrement, and mold. Typically, a lab uses a device to magnify an image of the
sample during inspection, such as a standard stereomicroscope or modern handheld digital USB mini-scope.
Either option gives ample visual magnification to conduct visual inspection. This examination is
generally carried out prior to sample homogenization, in order to identify debris before it would
otherwise be non-recognizable, mixed in with the botanical matrix.
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ample preparation varies according to the analytes being measured. In general, the
entire representative sample is mechanically homogenized (after visual inspection is complete). The
homogenization process ought to be conducted in a sterile manner when microbiological testing will be
conducted downstream. Sub-samples are then weighed into appropriate vessels, and an extraction liquid is
added to mobilize the product constituents, and potentially contaminants, into the liquid media
(solvent, acid, or buffer). Typically, this extract is further diluted into a test aliquot for analysis.
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annabis is tested to provide a measure of quality to the supply chain and ultimately
the end-user. Regulatory testing generally requires potency measurements so the product can be labelled
to inform the consumer, and also requires screening for residual contaminants such as pesticides, heavy
metals, processing chemicals, and microbes or microbial by-products, according to public-health
protection criteria.
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hromatography is historically and currently the name of the game when
measuring cannabinoid or terpene content in the certified laboratory setting. To determine cannabinoid
content in cannabis plant and infused products, liquid chromatography (LC) is often employed to quantify
both neutral and acidic forms of popular cannabinoids (neutral THC and CBD along with the acidic
counterparts, THCA and CBDA, for example). To measure the concentrations, a sub-sample (typically 0.5
grams or less) of the product is weighed and extraction solvent is added (often methanol). Gas
chromatography (GC) is typically utilized for terpenes analysis. In the absence of standardized methods
at a federal or international level, methodologies are quite varied and not widely shared.
P
esticide residuals on harvested cannabis plant material is a result of human
application or plant uptake from the environment. Mycotoxins are generally present when particularly
nefarious species of molds are present during cultivation, harvest, curing or storing phases of
production. Nevertheless, these both of these types of small molecules are typically tested by utilizing
methodology carried out by liquid chromatography tandem mass spectrometry (LCMS/MS). Gas chromatography
tandem mass spectrometry is also applicable in states with pesticide analytes not amenable to LCMS/MS.
These highly sophisticated, incredibly sensitive instruments are necessary due to the extremely low
quantities required for detection limits by many states.
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annabis plant and product samples are screened for ‘the big four’ metals in
many states. These metallic contaminants include arsenic, cadmium, lead, and mercury. Sources of these
contaminants can include soil, water, nutrient, compost tea, and other inputs during cultivation, or
trace contamination introduced during processing. Detection of heavy metals is often accomplished using
inductively coupled plasma mass spectrometry (ICP-MS), a sensitive instrument capable of detecting
extremely minute quantities. A strong acid is used to dissolve the plant or product matrix completely,
down to its elemental constituents, and a test aliquot is sampled by the analytical instrument.
W
hen raw cannabis plant material is extracted, concentrated, or otherwise processed
into oil, the process often utilizes butane, propane, ethanol or other chemical solvents as the carrier
for the target cannabinoids and terpenes. To determine if residual processing chemicals are present in
excess of the state action limits, test aliquots are partitioned into headspace vials and run on (GC)
instrumentation. Along with the extraction constituents such as butane, this assay also screens for
minute levels of contaminants such as benzene, chloroform, toluene, and xylenes.
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icrobial screening differs from chemical assays in several ways, but most notably considerations must be taken to maintain a sterile environment and avoid cross-contamination. Microbes are detected either by growing them to an extent they can be observed or amplifying and illuminating their DNA. Cannabis-industry specific assays have been developed to detect microbes regulated by many states, including PCR-based and microarray-based assays for E.coli, Salmonella, and Aspergillus.
In brief, in order to detect microbial contaminants, the sample is immersed in buffer to dislodge the microbial cells from the matrix, and an aliquot is removed to harvest microbial DNA for amplification. Samples will fail microbial testing if the species-specific analysis reveals E.coli, Salmonella, or Aspergillus present at a level of 1 colony-forming-unit (CFU) or greater. Broader categories such as total yeast and mold, total coliform, total Enterobacteriaceae, or total aerobic bacteria, are also sometimes required and often conducted using culture-based techniques.
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pon completion of all required laboratory testing, the product data are evaluated
against the action limit criteria. Test samples with no detections over any of the contamination limits,
and within potency claim margins, are deemed to pass and released in the seed-to-sale tracking system
for distribution. If a sample encountered a detection above any action limit, it fails the primary round
of testing and may be eligible for a remediation pathway according to individual state regulations.
Results are often communicated to the licensee directly by email, and also by means of a laboratory
client portal where all historical product CoAs are available. Additionally, results must be reported
via the state database. The potency values issued on the CoA are used to label the product and serve as
the primary conduit for communication of product constituents to the consumer.