Ocfentanil concentrations in hair: Comparative analysis in a lock of hair versus in a single hair

Abstract

The use of single hair offers some advantages for example in case of low amount of biological matrices [1] . Segmental single hair analysis was compared with segmental hair lock analysis to document a fentanyl analog-related death. A previous fatal case involving ocfentanil (OcF) was focused on conventional matrices and identification of metabolites [2] . The aim of this work was to complete toxicological data to document the chronic use of OcF in this case. A lock of hair was collected from the posterior vertex region during autopsy. After decontamination step, six hairs (H1 to H6) were collected from the lock and cut into 10-mm long hair segments (H x S1 to H x S10) with a sliding caliper [1] . The rest of the lock was cut into 2-cm lock segments (SS1 to SS5). Incubation step was performed in methanol, each sample was placed 10 minutes in ultrasonic bath then incubated overnight at 55 °C. LC-MS/MS analyses were performed using an API 4000 mass spectrometer (ABSciex ® ). Detection of OcF was performed in MRM mode and the monitored transitions were m/z: 371.3 → 105.1 and 188.2 (OcF) and 342.3 → 188.2 (fentanyl-d5, internal standard). Calibration curves ranged from 25 to 2500 pg/mg and from 0.1 to 20 pg/mm respectively for lock hair and single hair. Lock and single hair analysis results are presented in Table 1 . Hair lock analysis shows higher OcF concentrations in the first 2-cm segment and its decrease from root to tip. Single fiber hair analysis shows similar Results to those obtained with lock of hairs with maxima into first or second 1-cm segments and also decrease from root to tip. These profiles are in favor with a chronic use of OcF, although contamination by sweat during the agony period cannot be ruled out. Finally, similar profiles obtained both in lock of hair and in single hair demonstrate the interest of single hair analysis in a field where very few data are available. This is the first report to assess OcF in hair.