Confirmatory testing

Confirmatory testing is the second-stage laboratory analysis that identifies and quantifies a specific compound after a screening test returns a non-negative result.

It uses gas or liquid chromatography paired with mass spectrometry, which separates the sample and identifies each compound by its mass fragments rather than by antibody binding. The result names the exact molecule and its concentration, compared against a confirmatory cutoff that differs from the screening cutoff. Regulated programs require this step before a result is reported as positive.

For cannabinoids the method distinguishes THC-COOH, the target of standard panels, from CBD and other cannabinoids, which is why a non-negative screen is not the end of the process. A confirmed result is a finding about a specific metabolite in a specific sample; it does not indicate how the compound got there. Someone facing a confirmed result usually has the opportunity to discuss it with a medical review officer, whose role is to evaluate legitimate explanations under the program's rules.