Determination of fentanyl and norfentanyl in cerumen in the setting of postmortem investigation

Cerumen is an emerging alternative biological matrix in the field of forensic toxicology. An ultra‐high‐pressure liquid chromatography–mass spectrometry/mass spectrometry [UHPLC–MS/MS] method for the determination of fentanyl and norfentanyl in cerumen was developed and applied in a mixed drug toxicity fatal case. The method was found to be selective and sensitive (LOQ: 0.05 ng/mg for fentanyl and 0.02 ng/mg for norfentanyl), while validation included recovery, carryover, short‐term stability, matrix effect, accuracy, and precision (RSD%). Accuracy ranged from 83.1% to 103.5%, while intra‐ and inter‐day precision ranged from 8.6% to 13.1% and from 8.3% to 15.8%, respectively. Matrix effect experiments showed that matrix did not significantly affect signal intensity (82.3%–96.8%). Short‐term stability concerning sample extracts was found satisfactory. Fentanyl and norfentanyl were detected in cerumen at a concentration of 1.17 and 0.36 ng/mg respectively. The findings in cerumen corroborate the cause of death and suggest that cerumen is a potential specimen for detecting drugs of abuse in forensic cases.