Sending the urine sample off to a lab for analysis is standard procedure on DOT tests because on-spot instant testing is prohibited under the DOT regulations.

Once it arrives at the lab, an immunoassay screen with a 50 ng cutoff limit is performed as well as validity tests for creatinine, pH, specific gravity, nitrites, glutaraldehyde, and pyridine. Only if the sample tests positive for a given drug(s) will it undergo a confirmation GC/MS test. If a sample tests negative on the initial I/A screen, the test is over right then as a "pass" - no confirmation test will be performed.

And as long as you used an unexpired QF batch that has not been exposed to direct sunlight, it will pass the validity checks mandated by the Agency.