Identification and quantitation of kratom in the hair of a regular user of substances purchased on the darkweb

Abstract

Kratom is a natural substance with psychostimulant properties obtained from the Mitragyna speciosa species. Used today as a recreational drug, the leaves are either chewed, encapsulated, smoked or ingested as an infusion with lemon juice and sugar. Mitragynin, one of the 40 alkaloids identified in the plant, is found in 0.2% of the leaves and is considered a more potent analgesic than morphine. We present hair analysis of a 27-year-old man who self-reported daily consumption for five years of about 20 g of kratom, purchased on the darkweb, coupled with regular consumption of cannabis, GABAergic drugs and sporadically JWH-122. He donated voluntarily some hair samples. After receiving the procedure, he took himself a 3 cm long strand of brown hair, 2 months after his last consumption of JWH-122 and sent by postal way. Sample preparation was done using a published method (Fabresse et al. Drug Test Anal 2019;11:697–708). The hair strand was cut in two segments of around 1.5 cm. After decontamination, 50 mg of hair sample were incubated in phosphate buffer (pH 5.0). Liquid-liquid extraction (LLE) was performed using a mixture of heptane/ethyl acetate (v/v; 90/10) and carbonate buffer at pH 9.7. After agitation and centrifugation, a second LLE was performed by dichloromethane/isopropanol (v/v; 80/20). Organic phases were evaporated and of the dry residue was reconstituted in a mixture of water/ammonium formiate/formic acid. The screening method used an ultra-high performance liquid chromatography coupled to a benchtop Orbitrap (Q-Exactive, Thermo) operating in data-dependent acquisition mode (DDA). The same extract was then submitted to a targeted analysis by LC-MS/MS for quantitation (LCQ TSQ Vantage XP triple-quadrupole mass spectrometer, Thermo). The LC-HRMS method led to the identification of mitragynin and JWH-122. Mitragynin was quantified at 2235 pg/mg in the proximal part (A) and at 1717 pg/mg in the distal part (B). The metabolite of mitragynin, the 7-hydroxymitragynin was not identified. In parallel, using the same method, was positively quantified the JWH-122 in both hair segments (69 pg/mg in A; 103 pg/mg in B). The measured concentrations of kratom are compatible with the only concentrations described in the literature in a regular user (3 g/d) (Meier et al. Drug Test Anal 2020;12:280–4). In this case, mitragynin was measured in hair samples taken from different regions of the scalp with concentrations ranging from 1054 pg/mg to 2244 pg/mg. About the synthetic cannabinoid, the 27-year-old male self-reported a punctual JHW-122 consumption (20–40 mg/10 consecutive days). The values measured are also in accordance with the JWH-122 concentrations found in the literature based on eight hair samples from frequent users of THC-containing products or chronic abusers of classical drugs (range: 7–2800 pg/mg) (Salomone et al., Drug Test Anal 2014; 6(1–2), 126–134). Hair therefore appears to be a suitable biological matrix for the diagnosis and monitoring of kratom consumption.