Delineating the Nuts and Bolts of the USDA’s Hemp Testing Rules

Published on: 
Cannabis Science and Technology, January/February 2023, Volume 6, Issue 1
Pages: 28-34

This article addresses the US Department of Agriculture’s hemp testing rules and what laboratories should know regarding hemp testing. The author provides a short tutorial for laboratories and includes a section how laboratory information management systems (LIMS) can help.

In 2018, the Hemp Farming Act which proposed that hemp be removed from Schedule I and be reclassified as any other agricultural commodity was adopted into the 2018 Farm Bill, making hemp federally legal (1). Even though hemp is now legal in the US, its production is highly regulated and hemp testing laboratories must be aware of the relevant laws and regulations they must adhere to. This article delineates the nuts and bolts of the United States Department of Agriculture’s (USDA’s) hemp testing rules and what laboratories should know regarding hemp testing.

What Is Legal Hemp in the US?

Legal hemp is Cannabis sativa that contains less than 0.3% of the psychoactive cannabinoid tetrahydrocannabinol (THC) on a dry weight basis. Cannabis sativa containing more than 0.3% THC is classified as cannabis.

Here is where the line is drawn between hemp, which is legal, and cannabis, which remains a schedule I substance and is therefore illegal. The Controlled Substances Act (CSA) prohibits the “manufacture, distribution, dispensation, and possession of Schedule I substances except for federal government-approved research studies” (2). This delineates the need and relevance of hemp testing laboratories; to ensure that the 0.3% threshold for THC is not exceeded.

The Agricultural Improvement Act of 2018

The Agricultural Improvement Act of 2018 (2018 Farm Bill) removed hemp from the Drug Enforcement Administration (DEA) list of Schedule I controlled substances by adopting the Hemp Act (3). Consequently, the US Domestic Hemp Production Program was created to provide regulatory oversight for the hemp industry. The program mandated the USDA to create a regulatory framework and issue guidance to regulate the production of hemp. Following this, the USDA issued the Interim Final Rule (IFR) on hemp, which was published on October 31, 2019 (4). The US Food and Drug Administration (FDA) also allowed a 60-day comment period for the IFR. The 2020 growing season was used to test drive the IFR and together with the submitted comments from the public, the Final Rule (FR) was published in 2021 (5).

The USDA Issues Final Rule on Hemp

The Final Rule (FR) on hemp was published in January 2021 and took effect on March 22, 2021. It covers several key factors on hemp testing, including licensing requirements for hemp testing laboratories, sampling and testing procedures, handling of violations, reporting of test results, and the disposal of noncompliant crops. For hemp testing laboratories, the most critical consideration from the FR is the accurate testing of hemp samples and the calculation of THC concentration on a dry weight basis (5).

Scope of Hemp Testing Market

Grand View Research placed the value of the global hemp market at $4.13 billion in 2021. The value is expected to hit $16.75 billion by 2030, growing at a compound annual growth rate (CAGR) of 16.8% (6). This signals the growing demand for hemp testing services in the next couple of years to meet the regulatory requirements defined by the FR.

Not many laboratories are offering hemp testing services at the moment because the industry is still new, and the regulatory requirements are stringent. For example, hemp testing can only be offered by laboratories that are registered with the DEA. Thus, there’s a large opportunity of venturing into hemp testing and owning the space before it gets crowded.

Hemp testing laboratories as well as those aspiring to venture into the niche need to be conversant with the relevant rules as defined in the Final Rule. They also need to leverage the best technology to get ahead of the regulatory curve and become profitable in the soonest time possible. Here are the nine rules that apply to hemp testing.


Nine Cardinal Rules for Hemp Testing Laboratories

Hemp testing laboratories are of course free to test several other compounds as well. This means that they need to adhere to all the rules and regulations that apply to laboratories. However, there are some rules and regulations that are specific to hemp testing and must be adhered to as well. This begins with how hemp samples should be received, tested, and disposed of as well as how the test results should be disseminated. Some of the rules for hemp testing laboratories are below.

1. Mandatory DEA Registration

All laboratories that test for hemp must be registered with the DEA. Registration information can be accessed from the DEA’s Diversion Control Division website. The FR states that “Registration is necessary because laboratories could potentially handle cannabis that tests above 0.3% THC on a dry weight basis, which is, by definition, marijuana and a Schedule I controlled substance.” Fortunately, hemp testing laboratories had until the final day of 2022 to comply with this requirement.

The laboratories will also need to open a Hemp eManagement Platform (HeMP) account that allows them to manage and submit hemp information and report to the USDA, replacing the need to submit via email, mail, or fax. The USDA has published a directory for laboratories that have been certified by the DEA to test hemp that customers and other stakeholders can easily access.

2. Measurement of Uncertainty Must Be Calculated and Reported

The measurement of uncertainty (MU), is a measurement that expresses an acceptable degree of variance in a test result. It characterizes the limit of dispersion in the values (7). Hemp testing laboratories are required to calculate and report the MU when testing for THC in a sample. Possible sources of uncertainty need to be identified and their level of contribution quantified. This will be used to determine the overall measurement of uncertainty. The method for calculating the MU needs to include all possible contributors of uncertainty including the possible decarboxylation of THC (8).

3. Ensure Representative Sampling

The FR is very specific as to the parts of hemp that can be used as samples for THC testing. This is because THC, as well as other phytochemicals, are present in high amounts in the flowers, but exist in minimal amounts in the stems. Fortunately, the FR gave a greater allowance for the parts of hemp that can be tested, as compared to the IFR. Laboratories can now test samples from the buds and leaves, for as long as they are taken from at least 5–8-in. away from the main stem. Samples can also be picked from the central cola or terminal bud.

4. Sample Preparation for Hemp Testing

Once an appropriate sample has been obtained, it should be dried within 24 h. Note that THC is usually reported on a dry weight basis. It is important to minimize the variance that would arise if some laboratories report the THC level using a wet sample while others report using a dry sample. If the sample cannot be dried within 24 h, then it should be frozen at a temperature of -20 °C or lower.

The laboratory should grind the sample to a fine consistency prior to testing it. This is important for homogeneity. The sample should then be divided into two parts. One part should be used for testing while the other should be retained in case a retest is needed. The sample preparation procedure should be well captured in the laboratory’s internal standard operating procedures (SOPs) (9).

5. Use of Post-Decarboxylation Testing Method

The FR requires that hemp testing laboratories use a post-decarboxylation method when testing for THC in a hemp sample. Decarboxylation is the process through which acidic cannabinoids lose their acidity and become activated after they are exposed to heat. Raw hemp contains THC (as well as other cannabinoids) in its acidic forms. When exposed to heat, tetrahydrocannabinolic acid (THCA) is converted to the psychoactive cannabinoid THC. A testing method that does not consider the decarboxylation process will fail to capture the true concentration of THC in a given sample.

Gas and liquid chromatography are the approved post-decarboxylation methods for testing THC in hemp. Laboratories are free to explore other testing methods that factor in the decarboxylation process. However, laboratories will need to seek approval in writing prior to using any other method to test for THC (9).

6. The Negligence Threshold

The FR increased the negligence threshold for hemp testing from 0.5% to 1%. A hemp sample that tests above 0.3% is considered hot hemp. However, if the THC does not exceed 1%, it is not considered a negligent violation and hence is not penalized. However, the hot hemp still needs to be destroyed and disposed of. Previously, the FR allowed a negligence threshold of up to 0.5%. If a hemp sample tests above 1% THC, this is considered a negligent violation and subsequently the Licensed Producer (LP) is issued with a notice of violation. If an LP receives three consecutive notices within five years, the LP will be disallowed from taking part in the hemp program for the next five-year period.

7. Sharing of Test Results

Hemp testing laboratories are required to share the test results with the USDA, regardless of whether the THC limit is exceeded or not. The test results are shared through HeMP, so laboratories will need to create a HeMP account. The laboratories should also download Form 22 from the USDA’s Agricultural Marketing Services (AMS) website and use it to submit the THC results.

The test results must also be shared with the LP in a format that is most suitable for them. The results must be shared with the relevant state or tribe department of agriculture and should bear the stamp “official compliance.” Laboratories must store the test results for a minimum period of three years.

8. Hemp Retesting

The laboratories can conduct a retest of the hemp sample at the request of the LP. The same procedure for testing, as stipulated in the SOP, should befollowed. The results should also be shared with the three parties: licensed producer, the USDA, and the relevant department of agriculture. The LP should bear the cost of the retest.

9. Remediation of Hot Hemp

After testing, a laboratory is likely to come across some hot samples that will need to be destroyed and disposed of (10). Fortunately, the FR allows for the remediation of hemp, which means utilizing the hemp biomass. This prevents the LP from incurring huge losses. Different “dilution” methods can be used to remediate hemp. For example, the hemp can be shredded into biomass, and then a sample submitted for testing. The original testing method should be used for the retesting. The hemp biomass can be used for fiber or fuel if the THC level is compliant upon further testing.

As mentioned earlier, hemp testing is a potentially lucrative venture that has minimal competition at this point. That said, since the industry is being highly regulated there are several barriers to entry. Laboratories looking to venture into the industry should not be deterred by the hurdles, but should instead do all it takes to understand the legal landscape and implement measures to remain compliant with the relevant rules and regulations.

A LIMS Helps Hemp Testing Laboratories Meet Compliance Challenges Head On

A software as a service (SaaS) laboratory information management system (LIMS) for cannabidiol (CBD) and THC testing can help hemp testing laboratories get through the seemingly insurmountable compliance challenges (11). A LIMS helps laboratories track samples and manage test results while ensuring an optimum level of accuracy. A LIMS automates laboratory workflows, ensures efficiency, and minimizes errors. A LIMS supports the dissemination of test results to the relevant stakeholders while maintaining the record for the stipulated duration. A cloud-hosted LIMS enables remote access to laboratory data while providing enhanced data security (12). A cloud-based SaaS LIMS for CBD and THC testing reduces the operational costs of laboratories by eliminating the need to purchase IT infrastructure and hire dedicated IT personnel. Moreover, it enables laboratories to eliminate other upfront costs otherwise needed for deploying a traditional LIMS.


Hemp testing laboratories must meet the regulatory requirements set by the USDA that can be both specific and cumbersome. For example, all testing methods must take into account the decarboxylation of THCA to THC once the sample is exposed to heat. This restricts the testing methods that laboratories can use. Another challenge is balancing regulatory requirements with customer satisfaction. A hemp testing laboratory may develop a precise and accurate method to test THC that meets regulatory threshold for a well-defined measurement of uncertainty. However, this method may provide results that do not favor the customer, hence the laboratory can easily lose the customer on these grounds. At the end of the day, hemp testing laboratories must juggle between meeting regulatory requirements, satisfying customers, and at the same time ensuring the highest level of scientific accuracy. A cloud-based SaaS LIMS for CBD and THC testing enables hemp testing laboratories can meet compliance goals with ease while always assuring testing accuracy.


  1. H.R.5485 - 115th Congress (2017-2018): Hemp Farming Act of 2018 (accessed Oct 25, 2022).
  2. The schedule I status of Marijuana - Congress (accessed Oct 7, 2022).
  3. Infographic: Follow the USDA's new hemp testing rules with a laboratory information management system (LIMS)
  4. Enforcement discretion - interim final rule (accessed Oct 25,2022).
  5. USDA publishes final rule for the domestic production of Hemp
  6. (accessed Dec 2,2022).
  7. Farrance, I.; Frenkel, R. Uncertainty of measurement: A review of the rules for calculating uncertainty components through functional relationships
  8. Sgrò, S., Lavezzi, B., Caprari, C. et al. Delta9-THC determination by the EU official method: evaluation of measurement uncertainty and compliance assessment of hemp samples. Anal Bioanal Chem, 2021, 413, 3399–3410,
  9. Hemp testing guidelines issued January 15, 2021
  10. Hemp Disposal Activities
  11. Cannabis Lims Software for Medical Cannabis & Marijuana Testing Labs (accessed Nov 30,2022).
  12. Free ebook: A comprehensive guide to the USDA's Hemp Testing Rules

About the Author

Martha Hernández is a scientist at Martha is a chemist with expertise in diverse areas of analytical chemistry. Martha holds a bachelor’s degree in Clinical Chemistry from the Faculty of Medicine UANL and a master’s degree in Pharmacy from the Faculty of Chemical Sciences UANL, Mexico. Direct correspondence to:

How to Cite this Article:

Hernández, M., Delineating the Nuts and Bolts of the USDA’s Hemp Testing Rules, Cannabis Science and Technology®, 2023,6(1), 28-34.