• Steep Hill

Cannabis Flower vs. Concentrates: The Differences in Lab Testing

Cannabis consumer safety regulations vary by state due to a lack of federal regulation. As more states pass additional legislation, more cannabis and its derivative products will be purchased by consumers. To ensure that a product is safe for human consumption, rigorous testing needs to be completed. The safety of cannabis products concerns everyone, including the growers, distributors, and individuals who will eventually purchase and consume those products. However, cannabis products come in all shapes, sizes, and formats, and therefore the safety testing required must account for this variability.

Consumer Safety & Testing:

Traditionally, cannabis, in its simplest understanding, is known for being a plant that is consumed for its desirable medical and recreational effects. While the flower of the plant is commonly dried, ground, combusted, and inhaled, cannabis products and methods of consumption have become much more diverse since the discovery of the plant’s effects - and thus, new technologies for extraction have emerged. Trichomes, the semi-translucent hairs that coat the outside of a cannabis flower and the naturally occurring oils within them, can be extracted from the plant using various methods. These include mechanical separation, heat, or a chemical solvent, to name a few. These extractions can be processed into a wide variety of derivative formats that comprise the product category we have come to know as cannabis concentrates/extracts. Resin, Rosin, Distillate, Isolate, sauce, wax, budder, badder are just a few that we see in today’s markets. Cannabis concentrates can also be consumed in various ways, including combustion, vaporization, or ingestion. These products, where available, must also face the same kind of safety testing that is required for cannabis flower products, but lab testing procedures and testing methods can vary depending on which product matrix you are looking to test.

Sample preparation, dilution levels, test types, tolerance limits, and test methods are all aspects of the testing process that may differ slightly when a lab is performing testing on flower products versus concentrate products.

Sample preparation accounts for the various steps required to prepare a sample in a way that will allow the compound of interest to be properly measured by the analytical instrument designated for a specific test. Typically, with cannabis flower samples, the sample is milled, then solvents such as methanol are added to the milled sample, and the sample is then mixed and centrifuged to push out any undesired organic material from the final sample. The supernatant liquid is then transferred to a sample container such as an HPLC vial and loaded into the instrument. With concentrates, this process can be a little trickier. Firstly, packaging can be one of the first challenges of sample preparation for concentrates. Concentrates, particularly oils and vapes, will sometimes come in unique packaging designed for controlled dispensing, and this can present a challenge if a sample is submitted to the lab in its final packaging. To avoid this, analytical testing labs and their clients should always plan to have their samples submitted in packaging that allows for easy access to the sample material. Secondly, there is no milling required with concentrates, but there is a challenge related to proper homogenization of a concentrate sample. Concentrates come in a wide variety of consistencies, and some can be difficult to fully dissolve into the solvents required. Sometimes low heat may be required to achieve full dissolution, but this must be carefully done to avoid any degradation to the compounds you are trying to measure accurately. Additional dilution often becomes a necessity when working with products containing high concentrations of cannabinoids to avoid saturating the detectors on the instrument used for quantitation. This can be achieved with a properly calibrated set of pipettes and some additional math knowledge.

Test type requirements can also vary with flower versus concentrate products. For example, Residual Solvents testing is not required when testing flower products but almost always is for concentrate products. As mentioned above, when extracting concentrates from cannabis flower, many extractors choose to use a chemical solvent to aid in the process. Many states require that the final extracted product be tested to ensure the amount of solvent (Ethanol, Isopropanol, Butane, etc.) remaining in the product is below a specified tolerance limit for safety purposes.

Tolerance limits can also differ when testing flower versus extracts. Concentrate products can sometimes have slightly different tolerance limits for certain test types. Unfortunately, some extraction processes can lead to the concentration of undesirable contaminants in their product; therefore, it is imperative to ensure levels of contaminants in your starting materials are well below the acceptable tolerance levels prior to as well as post-extraction.

Test methods can also vary when performing analytical testing on cannabis flower versus concentrates. While they can be similar depending on the test, it is not always the case that a test method developed and validated for cannabis flower will work perfectly for all types of extracts. Therefore, labs should be prepared with SOPs, and test methods for handling a wide range of cannabis concentrates as well as flower. Sometimes if a novel extract format arrives at the lab, a verification exercise can be performed to determine the suitability of the test method for that product matrix.

Our Mission:

At Steep Hill, we understand the important aspects of what makes testing accurate and reliable, and that means knowing what is required to properly test a wide range of product varieties that exist in US markets today. As a cannabis lab testing network, Steep Hill is dedicated to ensuring consumer safety standards are met through rigorous testing practices, refined testing methodologies, and outstanding customer service. Scientific integrity rests at the heart of our network, pushing us to remain true to our goal of ensuring product safety for all parties involved in the production, distribution, and consumption of cannabis products – no matter which forms they may come in.


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