Work Item
ASTM WK68535

New Practice for proper estimation of concentrations of delta-9 tetrahydrocannabinol (D9-THC) in low-THC cannabis and cannabis products defined on a dry-weight basis.

1. Scope

Appropriate indicators are needed for proper determination of concentrations of D9-THC in low-THC cannabis and cannabis products defined on a dry-weight basis, to ensure accurate reporting of potency, reduce uncertainty in the marketplace, and ensure effective regulatory compliance.


low-thc resin hemp flower oil extract concentrates decarboxylated USDA rule rulemaking regulation statute


Local, state and national jurisdictions use varying practices and indicators for estimating the concentration of d9-THC in low-THC cannabis and cannabis products. In the US, these determinations respond directly to the statutory requirement under Federal law that low-THC cannabis (hemp) be tested for compliance using a procedure for testing, using post-decarboxylation or other similarly reliable methods, delta-9 tetrahydrocannabinol levels of hemp produced, alongside the provision that defines low-THC cannabis (hemp) as having a delta-9 tetrahydrocannabinol concentration of not more than 0.3 percent on a dry weight basis [7 U.S.C. 1639q]. Similar regulatory provisions exist in other jurisdictions. Reconciling these two requirements is challenging due largely to two problems that can lead to the overestimation of d9-THC in hemp crops, and therefore false findings of non-compliance: 1) One problem is due to the variability in hemp crops of THCA content (a portion of which converts to d9-THC under decarboxylation), even within strains and among genetically identical individuals. Though protocols exist for selecting and conducting sampling of crops, the hemp industry and current regulatory standards lack a generally accepted practice for analyzing the variance within such samples and representing it in the margin of error reported for the test results. Lacking such expertise or direction, regulators misinterpret test results as absolutes rather than estimates, with potentially severe consequences in cases of false positives for non-compliance. A practice for proper accounting of sampling uncertainty is needed to provide such expertise and direction. 2) A second problem is the variable nature of the rate at which the conversion of THCA to d9-THC occurs, which depends on factors such as the temperature and duration of the decarboxylation process. However, many if not most methods for indirect measurement of d9-THC assume a theoretical maximum decarboxylation rate of 87.7% (based on the molecular mass ratio of d9-THC to THCA) that exceeds the levels that can exist in actual decarboxylation testing, thus overestimating the amount of d9-THC in hemp crops with potentially severe consequences in cases of false positives for non-compliance. In order to establish similarly reliable methods to actual post-decarboxylation testing, an evidence-based standard for decarboxylation rates is needed.

The title and scope are in draft form and are under development within this ASTM Committee.


Developed by Subcommittee: D37.03

Committee: D37

Staff Manager: Jimmy Farrell

Work Item Status

Date Initiated: 06-03-2019

Technical Contact: Herrick Fox

Item: 000