Determination of ibogaine and noribogaine in biological fluids and hair by LC–MS/MS after Tabernanthe iboga abuse : Iboga alkaloids distribution in a drowning death case

Abstract

Tabernanthe iboga belongs to the Apocynaceae family. In this study, we report the case of a 37-year-old black male working as a security agent in Paris and found dead naked on the beach in Gabon after consumption of iboga. Autopsy revealed a drowning fatality and a myocardial abnormality (myocardial bridging). Samples of blood, urine, bile, gastric content, liver, lungs, vitreous, spleen and hair were taken. Biological fluids were liquid–liquid extracted with saturated NH 4Cl pH 9.5 and methylene chloride/isopropanol (95/5, v/v) in presence of clonazepam-d 4, used as internal standard. After decontamination with dichloromethane, hair was cut into small pieces then sonicated for 2 h in saturated NH 4Cl pH 9.5 before extraction by methylene chloride/isopropanol (95/5, v/v). After evaporation the residues were reconstituted in methanol/ACN/formate buffer pH 3, from which 10 μL were injected into an ODB Uptisphere C 18 column (150 mm × 2.1 mm, 5 μm) and eluted with a gradient of acetonitrile and formate buffer delivered at a flow rate of 200 μL/min. A Quantum Ultra triple-quadrupole mass spectrometer was used for analyses. Ionization was achieved using electrospray in the positive ionization mode (ESI). For each compound, detection was related to three daughter ions (ibogaine: m/ z 311.4 → 122.1, 174.1 and 188.1; noribogaine: m/ z 297.4 → 122.1, 159.1 and 160.1; clonazepam-d 4: m/ z 319.9 → 218.1, 245.1 and 274.1). Ibogaine and noribogaine were detected in all autopsy samples. Hair segmentation was not possible as hair was very short and frizzy. Concentrations of 1.2 and 2.5 ng/mg, respectively were detected. Neither other licit or illicit drugs nor alcohol were found. The presence of ibogaine and noribogaine in all autopsy samples was consistent with the recent absorption of Tabernanthe iboga, which was assumed to be responsible of the drowning fatality. The history of exposure, regarding hair analysis, is discussed. LC–MS/MS appears to be the best method for analyzing complex and poorly volatile alkaloids in autopsy samples and particularly in hair, due to the presence of a nitrogen ring and the relatively low concentrations to be measured.