The insanity of different states using different sampling schemes, analytical methods, different analytes, and different concentrations to regulate hemp growers has been discussed here before. With the promulgation of the U.S. Department of Agriculture’s Interim Final Rule in October 2019, some clarity has been brought to the problem. However, there are still problems with representative sampling, composite samples, and insuring there will be enough testing capacity to meet the demand for testing come harvest season. Here, some thoughts on how to solve this problem are shared.
In a recent column (1), I outlined the problem of different states using different sampling schemes, analytical methods, different analytes, and different concentrations to regulate hemp growers. With the promulgation of the United States Department of Agriculture’s (USDA) Interim Final Rule in October 2019 (2), some clarity has been brought to the problem. However, there are still problems with representative sampling, method differences, and insuring there will be enough testing capacity to meet the demand for testing come this harvest season. Some thoughts on how to solve this problem are discussed below.
Why Is Getting Hemp Testing Right so Important?
The answer: Because cannabidiol (CBD) is medicine and it should be tested like medicine. Hemp is an unusual crop because if it is being grown for CBD, rather than for its traditional uses as food and fiber, farmers are growing medicine. This is in part why the industry is so highly regulated. The absolute limit of 0.3% total tetrahydrocannabinol (THC) means that a farmer’s ability to sell their crop and make a living is affected by changes in total THC content of a few hundredths of a percent. I know of no other crop where such high stakes testing is required by law. Some farmers have literally bet the farm on hemp, weren’t able to sell their crops, and committed suicide as a result (3). Since Federal legalization of hemp (4) thousands of farmers across the US have taken the risk and invested heavily into planting hemp crops. We owe it to them, the backbone of our industry, to give them the best testing data and the fairest chance of being able to sell their crop.
Effects of USDA Interim Final Rule for Hemp Testing
My first article on hemp testing insanity was published in the October 2019 edition of Cannabis Science and Technology (CST) (1). In it I lamented the lack of guidance on hemp testing and how the variation in methodologies across states and third party laboratories produces inconsistencies in test results that are not fair to hemp farmers. As if they heard my call, within days of my article going to press the USDA promulgated an Interim Final Rule (IFR) for the regulation of the hemp industry nationwide (2). As far as hemp testing goes, the interim final rule made the five points below clear.
1. The Cannabinoid Being Regulated Is Total THC
Total THC is determined using this equation
Total THC = 0.877(THCA) + Δ-9 THC 
and the amount of total THC is not allowed to exceed 0.3% by dry weight. This is useful since, as I have pointed out (1), some states were regulating on total THC, others on THC, and others some combination of the two.
2. Margin of Error Has Been Taken into Account
The IFR defines an “acceptable hemp THC level” by adding the margin of error to 0.3%. For example, if for a given analyzer the error for the determination of total THC in dried hemp is ±0.04 weight percent, the acceptable hemp THC level for samples measured on that analyzer would be 0.34 weight percent total THC or less. This is welcome since all measurements contain error (5) so this must be taken into account when determining hemp legality. Previously, some states were not taking margin of error into account and were insisting on a strict 0.3% total THC limit, whereas others were allowing upwards of 0.1% error and passing samples that were upwards of 0.4% total THC.
- B.C. Smith, Cannabis Science and Technology 2(5), 10–13 (2019).
- 115th United States Congress, Senate Bill S.2667,” Hemp Farming Act of 2018.
- B.C. Smith, Cannabis Science and Technology 1(4), 12–16 (2018).
- B.C. Smith, P. Lessard, R. Pearson, Cannabis Science and Technology 2(1), 48–53 (2019).
- B.C. Smith, Cannabis Science and Technology 2(2), 12–17 (2019).
- B.C. Smith, Cannabis Science and Technology 2(3), 10–14 (2019).
- B.C. Smith, Cannabis Science and Technology 3(2), 10–15 (2020).
- B.C. Smith, Cannabis Science and Technology 2(1), 14-19 (2019).
- P. Atkins, Cannabis Science and Technology 2(2), 26–34 (2019).
- B.C. Smith, Cannabis Science and Technology 2(6), 28–33 (2019).
- C. Sánchez-Carnerero Callado, N. Núñez-Sánchez, S. Casano, and C. Ferreiro-Veraa, Talanta 190, 147–157 (2018).
- B.C. Smith, Cannabis Science and Technology 2(6), 10–14 (2019).
About the Columnist
Brian C. Smith, PhD, is Founder, CEO, and Chief Technical Officer of Big Sur Scientific in Capitola, California. Dr. Smith has more than 40 years of experience as an industrial analytical chemist having worked for such companies as Xeros, IBM, Waters Associates, and Princeton Instruments. For 20 years he ran Spectros Associates, an analytical chemistry training and consulting firm where he improved their chemical analyses. Dr. Smith has written three books on infrared spectroscopy, and earned a PhD in physical chemistry from Dartmouth College.
How to Cite this Article
B.C. Smith, Cannabis Science and Technology 3(3), 12–15 (2020).