Laboratory testing of cannabis is very important to ensure the quality and safety of the final products that reach the consumer market. When it comes to quality; laboratories are able to test cannabis by measuring the amount of cannabinoids like THC or CBD it has, as well as getting the full terpene profile which consumers can use to find the specific profile that gives them the best experience.
This profile is important since THC isn’t the only thing that has an influence on the effects of cannabis. Unfortunately not enough people know about this and look only for high THC values which leads to cannabis producers cherry picking labs that will return the highest, and not necessarily true, THC concentrations of the product.
In terms of safety; cannabis can contain many different dangerous substances. Here is a list and a brief description of what threats could be present in cannabis:
Pesticides – Some producers use chemical pesticides to protect their weed, and the effects of smoking pesticides aren’t fully known yet, which makes this a very important chemical to be on the lookout for. Unfortunately it’s not something we can easily remove ourselves at home like washing an apple before you eat it so you need a trusted laboratory to check for their presence.
Solvents – these are used to extract active compounds from the flowers like THC or CBD to then use in other products like vape liquids. There are many different solvents, each varying in how easy they are to handle and later remove, and how dangerous they are to humans. They are usually evaporated away, leaving just the oils behind, however this doesn’t always fully remove all of them.
PAH – Polycyclic aromatic hydrocarbons are organic molecules formed mainly of ring structures. These aren’t naturally found in cannabis or tobacco products but are created during incomplete combustion. Inhaling these can damage your lungs and cause long term respiratory problems, so it’s important to detect them before they can reach the customer as they can be a sign of poor product treatment and bad preparation.
Heavy Metals – As plants grow, they absorb many substances via their roots. This includes heavy metals that can be found in some soils. Those are toxic both to humans and to the plants that absorb them. However this property of taking up metals is used in a phytoremediation process where plants are used to clean soils from contaminants.
Mould and Mycotoxins – Many moulds naturally secrete mycotoxins which can have very unpleasant adverse effects even in small quantities. These grow in warm and humid conditions so it’s always a good idea to keep your weed in dry storage.
Bacteria – Commonly tested are E. coli, salmonella and many others. PCR tests are used to detect these which is more efficient than trying to grow entire cultures of bacteria. Just like moulds, they can produce toxins.
There are different ways to detect all of the above mentioned substances. Here are some of the methods used at Cannalabs and what they can detect:
ICP-OES ( Inductively coupled plasma atomic emission spectroscopy ) is a method used to detect metals like Lead, Copper, Chromium, Cadmium, Iron, Nickel, Silver, Manganese, Vanadium and Zinc in quantities as small as 0,6 mg/kg
It works by forming excited ions which, depending on what atoms they are, will emit a specific light signature that is recorded by the equipment. This can be used on samples like cannabis extracts, oils made from cannabis seed or products with cannabis additives.
HPLC-DAD (High-performance liquid chromatography and Diode array detector) HPLC is a method of separating compound mixtures as they travel through a pressurised liquid medium. They have different affinities for a solid phase found inside the column through which they travel, which means they travel at different speeds and elute at different times. These separated compounds are then detected using a diode array detector which shines UV light at the sample and a diode array records which parts of the light spectrum were absorbed. The absorption pattern allows us to identify what’s present in the sample.
We use HPLC-DAD to detect and determine the amount of cannabinoids like THC, CBD, CBA and others, found in the samples. Depending on the cannabinoid, we can record concentrations as low as 0,0001% and as high as 99%.
GC-MS (Gas Chromatography – Mass Spectroscopy) Gas Chromatography works in a similar way to HPLC, except the samples are separated while in a gaseous state. These separated samples are then forwarded to a mass spectrometer which can give us the mass of detected samples. With this method we can determine the terpene content of samples.
GC-FID (Gas Chromatography – Flame Ionisation Detector ) This method uses Gas Chromatography to separate the compounds in the sample. Next the separated compounds reach the FID that burns the sample in a hydrogen flame. This causes the organic compounds present to emit ions during the combustion whose intensity is proportional to the concentration found in the gas stream
This technique is used to detect traces of solvents like isopropanol, ethanol or methanol that might be remaining in the sample.
HPLC – FLD Samples are separated using liquid chromatography after which the individual sample is excited using UV light. Excited samples will want to get rid of the excess energy and will do so by emitting a characteristic for them wavelength that is observed and recorded by the apparatus.
With this we can detect a range of chemical compounds which are found in liquid state (like PAH).
LC-MS/MS This method separates samples using liquid chromatography and feeds the separated substances into the mass spectroscopy tandem apparatus. MS works by ionising samples, and using their varying weight but same charge to eliminate compounds that have a mass outside of a set range mass to charge ratio. After the first run, the resulting compounds that passed through the first MS are sent into a collision chamber where they are fragmented again into compound specific fragments which can be once again filtered through the next MS.
Drawback to this procedure is that you need to always prepare a template sample of the compound you’re looking for but the method makes up for this with very high precision. This allows us to detect the desirable flavonoids present in your cannabis products.