Stability testing for THC concentrates: method, formula and acceptance criteria

Cannabinoids degrade. Heat, light and humidity all act on them, which means potency at the point of manufacture is not the same claim as potency at the point of use. A stability study is how the gap between those two is measured rather than assumed.

What the study covers

Samples are held under distinct storage conditions — cool, dry, and room temperature — chosen to mimic how material is actually stored rather than how it would ideally be stored. The certificate of analysis issued at manufacture provides the baseline: potency and composition at time zero.

Testing at intervals against that baseline is what turns a shelf-life figure into something derived rather than asserted.

How potency loss is calculated

Potency loss is expressed as a percentage of the initial concentration:

Potency Loss (%) = [(Initial Concentration − Final Concentration) ÷ Initial Concentration] × 100

Stating it as a proportion of the starting value, rather than as an absolute difference, is what makes results comparable between materials that started at different concentrations.

What counts as a significant change

Acceptable loss is not a universal number — it depends on the material, its intended use, and the requirements of the regulator in the applicable jurisdiction. Stability testing is how an acceptable limit is established for a given material, and the shelf life that follows is the period over which the material is expected to stay within it under the stated storage conditions.

A commonly applied threshold for significant change in a finished drug product is a 5% change in assay from its initial value, or failure to meet potency acceptance criteria. Where a material is destined for a pharmaceutical application, those criteria are set by the applicable regulatory authority rather than by the supplier.