Hi there!
A properly prepared and stored THCA tincure should not trigger a positive result. When THC is consumed, the liver converts THC –> THC-COOH, which is then excreted in the urine; the drug panel tests for THC-COOH exclusively.
However, the metabolism of THCA starts just one step ahead of THC, i.e. THCA –> THC –> THC-COOH; a process called decarboxylation, which requires the application of very high heat, is necessary to convert THCA to THC. Therefore, without high heat, the THCA cannot continue down the pathway towards THC, then THC-COOH, and therefore will not trigger a positive result.
I hope this helps!
drkim