Detection of Carfentanil by LC–MS-MS and Reports of Associated Fatalities in the USA

Carfentanil is a mu (μ) opioid receptor agonist and is estimated to be ~10,000 times more potent than morphine in animal (non-human) models. It is not approved for human use and is only used to immobilize large exotic animals in veterinary medicine. In mid-2016, carfentanil emerged as a contaminant in street heroin in the USA and was central to a large number of emergency department visits and deaths. We describe an analytical method for the detection and quantification of carfentanil in whole blood specimens via a protein precipitation extraction with acetonitrile and liquid chromatography with triple quadrupole mass spectrometry. From 1 September 2016 to 1 January 2017, carfentanil was identified in 262 postmortem blood specimens. Blood concentrations ranged from 10.2 to 2,000 ng/L, with a mean concentration equal to 193 ng/L and a median concentration equal to 98.4 ng/L. We describe 13 fatalities from the Midwest region (Indiana, Kentucky, Michigan and Ohio) of the USA in which our laboratory performed comprehensive toxicology and in which carfentanil was detected and associated with cause of death. We recommend that any analytical method applied to the detection of this substance in human whole blood specimens be sufficiently sensitive to detect sub-100 ng/L concentrations and preferably utilize a 10-50 ng/L reporting limit.