Types of Residual Solvents for Cannabis

There are many types of residual solvents in the world, but the two most common residual solvents include the following:

Hydrocarbons

These include butane, propane, and hexane, which are commonly used as solvents for extracting cannabinoids from the cannabis plant in the production of concentrates.

Alcohols

These include isopropyl alcohol (IPA) and ethanol, which are commonly used as solvents in the production of tinctures, edibles, and other cannabis-infused products.

Other Solvents

Depending on the extraction method and conditions, other solvents like acetone, methanol, and chloroform could potentially be present as residuals, although these are generally not recommended due to their toxicity.

What are Residual Solvents and Why Test for it?

Residual solvents in cannabis refer to any solvents that are left behind after the extraction process of cannabinoids and other compounds from the plant material. Solvents are used in the extraction process to dissolve and separate the desired compounds from the plant material.

Common solvents used in cannabis extraction include butane, propane, ethanol, and CO2. While these solvents are generally considered safe, if they are not completely removed from the final product, they can be harmful to human health when ingested or inhaled.

In Canada, testing for residual solvents in cannabis is required by law under the Cannabis Regulations, which were established under the Cannabis Act. The regulations require that licensed producers of cannabis conduct testing for a variety of contaminants, including residual solvents. The maximum allowable limits for residual solvents are set out in the regulations, and products that exceed these limits cannot be sold legally in Canada.

Testing for residual solvents can help to ensure that cannabis products are of high quality and purity. Proper extraction methods and solvent removal can have a significant impact on the final product’s taste, aroma, and potency. By testing for residual solvents, producers can ensure that their products meet the desired quality standards.

Residual Solvents Analytes

At PPB Analytical, we test for purity for excellence. We test for 29 Analytes in the Residual Solvents testing, which can be viewed down below.

Acetic Acid

Acetone

Anisole

Butane

1-Butanol

2-Butanol

Butyl acetate

Carbon dioxide

Dimethyl sulfoxide

Ethanol

Ethyl acetate

Ethyl ether

Ethyl formate

Formic acid

Heptane

Isobutyl acetate

Isopropyl acetate

2-Methyl-1-propanol

3-Methyl-1-butanol

Methyl acetate

Methyl Ethyl ketone

Pentane

1-Pentanol

Propane

1-Propanol

2-Propanol

Propyl acetate

Tert-Butylmethyl ether

Triethylamine

Which Instruments are Used for Terpene Testing in Cannabis?

There are several instruments that can be used for residual solvent testing in cannabis. These instruments include:

Gas Chromatography (GC): GC is a commonly used analytical technique for residual solvent analysis in cannabis. It can identify and quantify residual solvents present in the sample.

High-Performance Liquid Chromatography (HPLC): HPLC is another commonly used analytical technique for residual solvent analysis in cannabis. It is particularly useful for analyzing polar solvents that are difficult to analyze using GC.

Fourier Transform Infrared Spectroscopy (FTIR): FTIR is a spectroscopic technique that can be used for residual solvent analysis in cannabis. It can identify the functional groups present in the sample and provide information about the identity of the solvents.

Headspace Gas Chromatography (HS-GC): HS-GC is a technique used for analyzing volatile compounds, including residual solvents, in solid or liquid samples. It can be used for cannabis testing as well.

Mass Spectrometry (MS): MS is a highly sensitive analytical technique that can be used for residual solvent analysis in cannabis. It can identify and quantify residual solvents present in the sample with high accuracy and precision.

The selection of the appropriate instrument for residual solvent testing in cannabis will depend on the specific requirements of the analysis, such as the type and concentration of solvents to be analyzed.

A Breakdown of Residual Solvent Analysis

Residual solvent analysis is particularly important for cannabis products, as solvents are commonly used in the extraction and purification processes of cannabis. In the section below, we have listed an example of the steps involved in residual solvent analysis:

Sample preparation: The first step in residual solvent analysis for cannabis is sample preparation. The sample is typically ground and homogenized to ensure a representative sample for analysis. Then, it is extracted with a suitable solvent, such as methanol or ethanol, to extract the residual solvents from the sample.

Headspace sampling: Headspace sampling is a common method of residual solvent analysis for cannabis. In this method, the sample is placed in a sealed vial, and the headspace above the sample is analyzed using gas chromatography.

Gas chromatography: Gas chromatography is also commonly used to analyze residual solvents in cannabis. The extracted sample is analyzed using gas chromatography with a flame ionization detector (FID) or mass spectrometry (MS) detector.

Calibration: Calibration is an essential step in residual solvent analysis for cannabis. It involves analyzing standard solutions with known concentrations of residual solvents to create a calibration curve.

Data analysis: The data collected during the analysis is then analyzed to determine the amount of residual solvents present in the sample. The amount is typically reported in parts per million (ppm) or micrograms per gram (µg/g) of sample.

Compliance with regulatory limits: Like other products, cannabis products must comply with regulatory limits for residual solvents. The analyzed results should be compared to these limits to determine if the product is compliant.

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