A 22-year old male with a history of heroin use was found at home with severe respiratory depression that was successfully reversed by paramedics with the opioid antidote naloxone. At the hospital, a urine opiate immunoassay screen was negative and the urine benzodiazepine immunoassay screen was positive. A subset of the liquid chromatography-tandem mass spectrometry (LC-MS/MS) benzodiazepine confirmation results are shown in the figure below.
Only the failing multiple reaction (MRM) ion ratio prevented reporting a false positive confirmation result for the triazolam (Halcion) metabolite. The calculated 2-hydroxytriazolam concentration in the patient sample was above the positive confirmation cutoff value and the relative retention time (RRt) was correct, but the failed ion ratio correctly indicated that there was no 2-hydroxytriazolam in the sample.
Further investigation revealed that the patient had ingested the designer opiate U47700, purchased over the internet. We hypothesize that the false-positive benzodiazepine screen and the deceptive peaks at the 2-hydroxytriazolam RRt were caused by a U47700 metabolite, as we subsequently found the same pattern in the urine of two other patients with a history of U47700 exposure. For more information, see Schneir et al, Clinical Toxicology 2017;55:51-54.
Related content: See articles from Kara Lynch, PhD and Adam Zabell, PhD, in the May issue of CLN’s Focus on Mass Spectrometry about LC-MS/MS quality assurance and metadata monitoring.