Official US Government Icon

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.

Secure Site Icon

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

The latest general information on the Coronavirus Disease 2019 (COVID-19) is available on For USDOT specific COVID-19 resources, please visit our page.

DOT Rule 49 CFR Part 40 Section 40.177

Subpart H - Split Specimen Tests

§ 40.177 What does the second laboratory do with the split specimen when it is tested to reconfirm the presence of a drug or drug metabolite?
(a) As the laboratory testing the split specimen, you must test the split specimen for the drug(s)/drug metabolite(s) detected in the primary specimen.
(b) You must conduct this test without regard to the cutoff concentrations of §40.87.
(c) If the test fails to reconfirm the presence of the drug(s)/drug metabolite(s) that were reported positive in the primary specimen, you must conduct validity tests in an attempt to determine the reason for being unable to reconfirm the presence of the drug(s)/metabolite(s). You should conduct the same validity tests as you would conduct on a primary specimen set forth in §40.91.
(d) In addition, if the test fails to reconfirm the presence of the drug(s)/ drug metabolite(s) reported in the primary specimen, you may send the specimen or an aliquot of it for testing at another HHS-certified laboratory that has the capability to conduct another reconfirmation test.
[65 FR 79526, Dec. 19, 2000, as amended at 73 FR 35973, June 25, 2008]
Last updated: Wednesday, June 21, 2017