Unresolved discrepancies between cannabinoid test results for infant urine.

Background: False-positive drug screen results for tetrahydrocannabinol (THC) have been observed. This study investigated the rate of unconfirmed positive screen results in infant and noninfant urine samples and evaluated possible reasons for differences.

Methods: The rate of unconfirmed positive THC screen results for urine samples was determined retrospectively in 2 independent data sets (n = 14,859, reference laboratory; n = 21,807, hospital laboratory) by comparing positive immunoassay-based drug screen results with the associated results of confirmation tests.

Patterns of free (unconjugated) buprenorphine, norbuprenorphine, and their glucuronides in urine using liquid chromatography-tandem mass spectrometry.

Patterns of buprenorphine and metabolites were examined in 1946 positive urine samples analyzed by liquid chromatography-tandem mass spectrometry for free (unconjugated) buprenorphine and norbuprenorphine (quantitative, 2 to 1000 ng/mL) and buprenorphine-glucuronide (B3G) and norbuprenorphine-glucuronide (N3G) (semi-quantitative, 5 to 1000 ng/mL). Two distribution patterns predominated with 49.1% positive for norbuprenorphine, B3G, and N3G and 41.