The objectives of this study included 1) the development of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and subsequent liquid chromatography–mass spectrometry/mass spectrometry analysis; 2) validation of the method, following the American Academy of Forensic Sciences Standards Board (ASB) standard 036 requirements; and 3) application to authentic liver specimens for 34 analytes, including fentanyl, metabolites, and fentanyl analogs.
Since 2013, drug overdose deaths involving synthetic opioids (including fentanyl and fentanyl analogs) have increased from 3,105 to 31,335 in 2018. Postmortem toxicological analysis in fentanyl-related overdose deaths is complicated by the high potency of the drug, often resulting in low analyte concentrations and associations with toxicity, multidrug use, novelty of emerging fentanyl analogs, and postmortem redistribution. In the current study, the bias for all 34 fentanyl analogs did not exceed ±10 percent for any of the low, medium, or high concentrations and the percentage of CV did not exceed 20 percent. No interferences were identified. All 34 analytes were within the criteria for acceptable percent ionization suppression or enhancement with the low concentration ranging from −10.2 percent to 23.7 percent and the high concentration ranging from −7.1 percent to 11.0 percent. Liver specimens from 22 authentic postmortem cases were extracted and analyzed, with all samples being positive for at least one target analyte from the 34 compounds. Of the 22 samples, 17 contained fentanyl and metabolites plus at least one fentanyl analog. The highest concentration for a fentanyl analog was 541.4 μg/kg of para-fluoroisobutyryl fentanyl (FIBF). The concentrations for fentanyl (n = 20) ranged between 3.6 and 164.9 μg/kg with a mean of 54.7 μg/kg. The fentanyl analog that was most encountered was methoxyacetyl fentanyl (n = 11) with a range of 0.2–4.6 μg/kg and a mean of 1.3 μg/kg. The QuEChERS extraction was fully validated using the ASB Standard 036 requirements for fentanyl, metabolites, and fentanyl analogs in liver tissue. (publisher abstract modified)