Nitrite tests are part of the validity tests performed on all urine specimens submitted for drug testing. Validity testing can detect certain attempts to cheat during unsupervised specimen collection. The nitrite test looks for oxidizing substances such as the nitrites themselves or other oxidizing products found in the household or available on the Internet.
Nitrites are undetectable in normal urine, and their concentration is relatively low even in urinary tract infections. Positive results are consistent with an attempt to adulterate the specimen by adding oxidizing agents. Adulteration attempts are considered to be equivalent to a positive drug test result.