Recently, we are witnessing new and emerging growth in Cannabis products’ Quality Control testing laboratories as result of new regulatory requirements. In addition, patients/clients expectations for safe and effective cannabis products increased the awareness for quality and standardization within the cannabis industry.

From an analytical lab perspective, Cannabis is definitely a challenge. It contains sticky and lipophilic materials which are hard to work with, and contains a lot of chlorophyll and waxes.

Cannabis floral tops usually contain 20-30% Cannabinoids, 2-3% Terpenes (light and heavy) and are 60-80% lipids, waxes, carbohydrates, flavonoids, alkaloids  and other materials (by dry weight). In the process of specific Cannabis materials concentrates preparations and isolation, such as CBD and THC, the verity of molecules narrows down.

Cannabis physical, analytical and microbial testing

The standard physical, analytical and microbial tests being performed for Cannabis dry flowers and final product are:

Moisture (water) content


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In order to ensure proper drying, curing and storage conditions, to minimize the risk for mold formation, to control microbiological levels and to support product shelf life, water content in the Cannabis flowers should be controlled and tested during and after the drying and curing process. In addition, several Cannabis products manufacturing processes require a specific level of water content in the starting material. Water content is measured and tested using KF (Karl Fischer) apparatus or LOD (Loss On Drying).

Cannabinoids and Terpenoids analysis

Usually performed using LC or GC (coupled with UV or MS detectors) or by IR spectrometry. The concentration of Cannabinoids and Terpenoids in the starting  material will determine which is the most preferable industrial processing and which Medical Cannabis final product will be manufactured. For example – a high concentration of CBG and CBD in the starting material will be difficult for separation via supercritical extraction methods.

” Simple” analytical methods can be used  for identification of major Cannabinoids (THC, CBD, CBN and their acidic forms) , while more “sophisticated” analysis methods will be used for minor Cannabinoids analysis and detection.

Cannabis Pesticides and Herbicides

As any other agricultural crop and/or product, Cannabis plants and materials should also meet Pesticides and Herbicides release specifications.

Cannabis may poses a greater risk, due to the fact it is usually consumed via heating and inhalation and goes from the lungs into the blood stream (by smoking or evaporation). Pesticides and Herbicide detection and analysis is very challenging due to the complexity of Cannabis material and is usually performed using GCMS (Gas Chromatography Mass Spectrometry). Several Pesticides and Herbicides are considered to resemble Cannabinoids’ polarity and boiling points (temperature) and might build up as the process tends to isolate specific Cannabinoids. Pesticides and Herbicides can be detected at low PPM levels, and may require a more complex sample preparation method.  Cannabis Pesticides and Herbicides method preparation is usually performed by quenchers kits, or by SPE to pre purify the sample prior to injection into the relevant analysis system.

Cannabis Microbiological screening

Medical Cannabis is commonly used for HIV, cancer and other medical conditions where patient’s immune system is “knocked out”. High microbial levels and/or pathogenic micro-organism and/or toxins metabolites in the product may risk patients lives. Several fungus types (especially black fungus), Mycotoxins should be detected and analyzed as part of Cannabis release specifications and Quality Control.  Microbiological screening utilizes generic methods developed and used in the food and pharmaceutical industries. Mycotoxins are harmful at the PPB level and the sample preparation is relatively complex. After the matrix has been extracted and filtered, and then tested via HPLC and GC with detection limits around 2-5 ppb, or by ELISA antibody kits with the detection limits down to single ppt’s.

Residual solvents

In cases where solvents were used as part of the cannabis products processing, such as in the extraction stages, solvent residuals in the final product should meet the acceptable criteria. The FDA already published the criteria for residual solvents in API’s for pharmaceutical use. The solvent limits are between single ppm’s and up to 0.5% by weight. Due to the fact that in the past decade, Cannabinoid formulations contain  high concentration of API’s ( 500-1500 mg’s per day), Cannabis products manufacturers have to take caution not to exceed the daily intake limit (maximal quantity of solvents allowed for a daily dose).

Heavy metals

As with many other plants, Cannabis draws metals from the ground. Elemental impurities also tend to accumulate during the extraction and purification process. Metal traces analysis is performed by ICP.  The tests are usually performed for Mercury, Arsen, Lead and Cadmium and their limit depends on the Cannabis product administration route. For oral administration the limits are 0.5 ppm for Cadmium and lead, 1.5 ppm for inorganic Arsen and 3 ppm for inorganic Mercury.

Cannabinoids

Cannabinoid concentrations such as THC, THCa, CBD, CBDa, CBN, CBC, CBG and others should meet the concentration ranges specified on the product label, based on Cannabis product usage purpose (recreational, medical), patients medical condition, age etc. Cannabinoid concentrations can be tested using HPLC and LCMS.

Terpenes

In addition to their contribution to Cannabis taste and aroma, it is well known that Terpenes increase Cannabinoids’ therapeutic effects, receptor affinity and also have their own health benefits. Terpenes can be detected using GC (Gas Chromatography).

The Future

Procedures should exist for every step of the Cannabis analysis and testing processes. Identification of the same contamination type on each step may require different methods especially for Herbicides and Pesticides GC analysis. (Cannabis plants natural products are chemically resembles to contaminates).

The Cannabis industry is relatively “new” for most of the QC labs, and testing methods are being improved and changed frequently.  Having an experienced analytical chemists and technicians may be helpful in cases of troubleshooting, new analytical methods development, out of spec. results etc.

(Original article published at: cannabisgxp.com)

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