CBD and Cannabis Laboratory Analysis and Testing

It is a long way from the cannabis plant to CBD commodities like oils, cosmetics, drugs or liquids for CBD vapes.

Creating high-quality cannabis products starts with careful selection of the right plant genetics for the product of interest. Generally, it takes 10-32 weeks from planting the seed until harvest of the full-grown plant.

Cannabinoids like CBD are most concentrated in the flowers of the plant. After harvesting, the hemp is usually dried and trimmed to isolate the CBD-rich flowers.

Extraction of the flowers allows enrichment of cannabinoids and terpenes, which is required for the formulation of many CBD products.

Several different cannabis extraction techniques named for the solvent used in the process exist. Each has its own advantages and disadvantages and yields cannabis extracts with specific characteristics (more details in FAQ).

The most common cannabis extraction methods are CO₂ extraction, hydrocarbon extraction and ethanol extraction. Independent of the method, the cannabis extraction process is not entirely selective towards cannabinoids and terpenes. Common impurities found in extracts are chlorophyll, waxes and lipids.

Impurities like waxes and lipids are removed by a process called "winterization". The extract resulting from CO₂ or hydrocarbon extraction is dissolved in ethanol and cooled, allowing impurities to precipitate. Subsequent filtration yields an ethanolic solution rich in terpenes and cannabinoids including the CBD precursor cannabidiolic acid (CBDA). Winterization is not necessary in the case of extraction with cold ethanol.

Controlled heating of the CBDA-rich solution allows for conversion of CBDA to CBD by a process called decarboxylation. This process can be combined with distillation for further purification.

In a first step, the ethanol from the winterization is removed by evaporation, while in a second, the residue is distilled. Heating during distillation triggers decarboxylation, converting CBDA to CBD. Subsequently, the CBD is evaporated, condensed and collected to form the so-called distillate.

If pure CBD is required, the distillate is further purified by crystallization. The distillate is dissolved in a hydrocarbon solvent such as butane or pentane. CBD crystalizes out from this solution upon cooling. The resulting product is called isolate.

If the explicit water content needs to be measured, Karl Fischer (KF) titration is the method of choice. This technique is based on a specific chemical reaction that is highly selective to water. Measured values are consistently lower than the ones obtained with moisture analyzers since no other volatiles register.

METTLER TOLEDO has decades of experience with KF water determination and offers tailored options for every need. KF titrator models like the Compact C30S or the Compact V30S can be used in stand-alone mode or be combined with an InMotion KF autosampler for fully automated analysis.

For measuring cannabis product moisture content, METTLER TOLEDO offers moisture analyzers like the Halogen Moisture Analyzer HX204.

Unlike KF titrators, halogen moisture analyzers do not require chemicals or complex instrumentation. They consist of a weighing unit and halogen heating unit. A sample is placed on the sample pan and dried under precisely controlled temperatures. The weight loss on drying (LOD) is measured over time and the moisture content is calculated automatically.

Heat-induced chemical processes that have an influence on sample weight, for example cannabinoid decarboxylation, are a potential error source. Referencing moisture analysis to KF titration allows for correction of weight loss caused by anything other than water evaporation.

Water and moisture content are also accessible by thermogravimetric analysis (TGA). In contrast to drying ovens and halogen moisture analyzers, stand-alone TGA measurements require much less sample. Furthermore, the possibility to conduct analyses under reduced pressure can limit the need for heating, which helps to avoid decomposition of heat-sensitive samples.

A TGA instrument can be coupled to an evolved gas analysis system such as a mass spectrometer or a micro GC/MS to allow the distinction of water from other volatile substances or decomposition products. The TGA/DSC 3+ allows precise and reliable thermogravimetric analyses.

Measuring the density of an extract allows correct product formulation. The more exact the value, the more precise the extract can be diluted with a carrier material. This can increase product quality and reduce production costs.

Since most extracts are highly viscous, they are hard to handle, making density measurements difficult. With METTLER TOLEDO heated autosamplers SC1H and SC30H, it is possible to decrease sample viscosity, enabling safe, precise, repeatable, and automated analysis of cannabis extracts.

Many cannabis extraction laboratories reuse extraction solvents for economic as well as ecologic reasons. METTLER TOLEDO density meters such as the portable Densito allow quality control of solvents recovered from the extraction process and a Disp-X large bottle top dispenser can help measure specific amounts of liquids for various tasks.

Alternatively, refractive index measurements using, for example, the Easy R40 refractometer also allow purity tests of recovered solvents. The measurement of density or refractive index allows determination of water content or other solvent impurities.

Many CBD-containing consumer products such as creams, oils, lotions or CBD e-liquids are routinely subjected to density or refractive index measurements as part of the quality control process. The compact and precise Easy D40 digital density meter and Easy R40 refractometer enable easy measurements. A specially designed syringe adapter for loading density meters allows straightforward analysis of pasty and viscous CBD samples.

The peroxide value is an important quality parameter for oils and fats. Light, temperature, oxygen, water and enzymes are responsible for oil or fat spoilage. The peroxide value indicates the oxidative rancidity of oils, meaning the extent of oxidation undergone by the sample. It is expressed as milliequivalent oxygen per 1000 g of oil. The peroxide value is accessible via iodometric sample titration using thiosulfate as the titrant.

METTLER TOLEDO offers well-established solutions such as the automatic titrator G20S with a DMi140-SC combined platinum ring electrode for convenient and precise peroxide value determination.

During storage, processing or heating of oils and fats, free fatty acids (FFA) can form due to hydrolysis reactions. The FFA content is defined as the weight of oleic acid, or – depending on the type of oil – lauric or palmitic acid in 100 g of sample. It is determined by means of non-aqueous titration with ethanolic potassium hydroxide as a titrant. The titration may be performed conveniently by a METTLER TOLEDO G20S titrator with a DGi113-SC combined pH glass electrode for non-aqueous solvents. Note that the analysis might be compromised if CBDA is present in the sample, since CBDA contains a carboxylic acid moiety.

The iodine value of an oil is the mass of iodine in grams that is consumed when added to 100 g of oil. Since iodine is very reactive towards unsaturated fatty chains, the knowledge of the iodine number allows for determination of an oil's level of unsaturation. The iodine value is determined via iodometric titration. It may be performed quickly and accurately with a METTLER TOLEDO G20S titrator and a DMi140-SC platinum ring electrode.

The saponification value of cannabis oil is connected to the average chain length of the fatty acids contained in the oil. The higher the value, the lower the average fatty acid length. The saponification value is obtained by back titration of excess potassium hydroxide with hydrochloric acid after saponification of the fats at high temperature. It can be precisely evaluated using a METTLER TOLEDO G20S titrator with a DGi 115-SC combined pH glass electrode. Again, the analysis might be compromised if free fatty acids or CBDA are present in the sample, since these compounds contain a carboxylic acid moiety.

Volumetric Karl-Fischer titration can be used to assess the water content of cannabis oil. The sample is dissolved in a methanol/chloroform solvent mixture for optimal dissolution. The titration can be performed quickly and reliably with a METTLER TOLEDO Compact V30S titrator using a DM143-SC double platinum pin electrode.

Pesticide residues in cannabis products present a risk to consumer health. They are determined using liquid or gas chromatography in combination with mass spectrometry (LC-MS, GC-MS). Accurate standard solutions are required to qualify and quantify over 100 different pesticide residues.

Cannabis plants can absorb heavy metals from contaminated soil. Typical examples that are problematic to human health include lead, mercury, arsenic and cadmium. Common analytical methods for trace metal analysis include atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS).

Mycotoxins are metabolites produced by yeasts or molds. Because they can be harmful to humans, mycotoxin screenings are routinely performed with the help of gas chromatography (GC) and high performance liquid chromatography (HPLC).

Cannabinoid potency must be determined to allow consumers to correctly dose the amount of medical cannabis administered. Cannabis potency testing is usually carried out via gas chromatography (GC) and high-performance liquid chromatography (HPLC).

Solvent residues remaining from cannabinoid extraction or processing pose a risk to human health. Extracts as well as products are tested for solvent residues using gas chromatography with a flame ionization detector (GC-FID) or headspace gas chromatography coupled to a mass spectrometer (HS-GC-MS).

Terpenes are organic compounds that are responsible for the unique fragrance of cannabis. These compounds are also being studied in the context of the medical benefits provided by the cannabis plant. Terpene profiling, routinely achieved via gas chromatography coupled with mass spectrometry (GC-MS) in combination with cannabinoid profiling, can be used to determine the cannabis plant strain.

EasyMax, OptiMax, RC1 reaction calorimeters and RX-10 provide 24/7 precise control and recording of process parameters, including the capture of crystallization enthalpies so that scientists can confidently identify Critical Process Parameters (CPPs).

A probe-based imaging tool with image analysis captures high-resolution images and calculates crystal, particle and droplet size distributions as they naturally exist in process.

Statistically, highly robust particle mechanism finger printing through particle size and count expedites successful scale-up from lab to fully ATEX rated plant scale.

In-situ Raman spectroscopy provides molecular and structural information to help scientists understand complex polymorphic landscapes and select process parameter to achieve the desired crystal form consistently.

Real-time FTIR spectroscopy provides key information for concentration and supersaturation levels, metastable zone width, desupersaturation kinetics and crystallization endpoint so that crystallization processes can run repeatedly to a desired target endpoint every time.

This robust platform enables interoperability between PAT tools so that all probes and reactors can communicate with each other and the resulting analytical information (size, form, supersaturation, etc.) becomes a useful process control parameter.