Detection of Fentanyl and Fentanyl Analogs.

Illicitly manufactured fentanyl and fentanyl analogs have led to a drastic increase in opioid related overdose deaths. Sensitive detection of fentanyl exposure requires specific assays that target fentanyl and its major metabolite norfentanyl. Fentanyl immunoassays have varying sensitivity to detect fentanyl analogs but many of the more prevalent analogs are not detected by routine fentanyl testing methods. This review focuses on the current state of both immunoassay and mass spectrometry-based testing methods for the detection of fentanyl and fentanyl analogs.