Cannabis potency can be measured by profiling cannabinoids. These molecules provide many of the therapeutic and psychoactive (∆9-THC) effects felt when inhaling or ingesting cannabis. Cannabinoids occur naturally in glandular trichomes distributed across the surface of the cannabis plant. Their profiles can vary depending on the plant tissue type, sex, genotype, maturity, growth conditions (i.e. nutrition, light level, temperature, etc.), harvest time, and storage conditions. The most abundant cannabinoids are tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN), and cannabigerol (CBG).

Cannabinoids are classified as either neutral or acidic. Most of the THC present in the cannabis plant is in the form of THC acid (THCA) – a non-psychoactive precursor of THC. Only when it is heated (or with extended exposure to light) is THCA converted into its psychoactive successor. Therefore, total THC is reported as (THCacid + THCneutral).

At Zen Labs, we use high performance liquid chromatography (HPLC) to measure cannabinoid content from cannabis samples. We profile THC and CBD as required by Health Canada. We can screen for a large number of other cannabinoids at the customer’s request.


Metals such as lead (Pb), cadmium (Cd), and mercury (Hg) are termed ‘heavy’ metals because of their high densities, while arsenic (As) is included because it has similar properties. Because of their chemical properties, heavy metals have a tendency to bioaccumulate in plant and animal tissue. In humans, higher concentrations may cause genetic, morphological, and physiological abnormalities including disruption of vital organs, mutagenic effects, and increased mortality.

Heavy metals occur naturally in soils, and the presence of heavy metals in inorganic fertilizers (i.e. elevated levels of Cd in rock phosphate fertilizers) is well documented. The cannabis plant has a great capacity to absorb and accumulate heavy metals from its growing medium. So much so that cannabis plants are often used in phytoremediation of contaminated soils!

We use acid digestion, followed by inductively coupled plasma mass spectrometry (ICPMS) to screen for lead, cadmium, mercury, and arsenic from cannabis samples.

Acceptable limits (USP 2232/Ph.Eur. 2.4.27):

Pb = 1.0 ppm

Cd = 0.5 ppm

As = 1.5 ppm

Hg < 1.5 ppm


Microbes are ubiquitous in most environments and thus, the presence of microbes on plant material is not uncharacteristic. This is especially true for cannabis grown indoors, as high temperature and high humidity environments are conducive to microbial growth. Some microbes exist as beneficial or mutual symbionts and pose no risk to plant or human health, while others may exist as harmless spores exhibiting no vegetative growth.  However, some types such as Botrytis sp. (causing the common “bud rot” disease) may cause damage to the plant itself, while others are pathogenic to humans. Common pathogenic microbes that may pose risk to human health include E.coli, Salmonella, Pseudomonas aeruginosa, Shigella, and Staphylococcus aureus. The presence of these microbes or general microbial infection may be an indication of poor growing practises such as over-watering, over-crowding, poor air circulation, contaminated water, standing water, and poor sanitation and hygiene practises.

We use a variety of plating and microscopic techniques to determine if there is any microbial contamination of the cannabis sample.

Acceptable limits (USP 61, USP 62, USP 2203)

Total plate count (TPC) < 200 000 cfu/g

Total combined yeast and mold count (TCYMC) < 2 000 cfu/g

Bile tolerant gram negative bacteria (BTGN) < 2 000 cfu/g

Absence of E.coli

Absence of Salmonella

Absence of Pseudomonas aeruginosa

Absence of Shigella

Absence of Staphylococcus aureus


Aflatoxins are a group of mycotoxins (toxic fungal metabolites) produced by several Aspergillus species of fungi. Similarly, ochratoxin A is a mycotoxin produced by Penicillium and Aspergillus fungal species. Both aflatoxins and ochratoxin A are extremely toxic to human health, causing acute mutagenic, teratogenic, immunosuppressive, and carcinogenic complications. Species of Aspergillus and Penicillium are omnipresent, especially in soil.

We use high performance liquid chromatography (HPLC) to screen cannabis samples for Aflatoxin B1, Aflatoxin B2, Aflatoxin G1, Aflatoxin G2, and Ochratoxin A.

Acceptable limits (USP 561):

Aflatoxin B1 < 5 ppm

Aflatoxins (B1+B2+G1+G2) < 20 ppm

Ochratoxin A < 20 ppm


The Pesticide Management Regulatory agency (PMRA) lists pest control product that have been registered and approved for use on cannabis. The use of unregistered pesticides on cannabis may result in serious harm to users.

Information about what pest control products have been approved for cannabis can be found here.

Please contact us for more information on pesticide screening.

Foreign Matter/Stems Screening

We use microscopic screening to identify foreign matter and abundance of stems:


Cannabis samples are dried in an oven. Moisture content should not be more than 15% (OMC 2007)

Other cannabis testing services we will provide:

  • Terpenes
  • Organic matter content
  • Residual solvent analyses
  • Edibles and oils
  • Soil, water, and feed testing

Please contact us for more information.

© Copyright ZenLabs 2018. All rights reserved.