Synthetic cannabinoid isomers characterization by MALDI-MS³ imaging: Application to single scalp hair

New designer drugs, as synthetic cannabinoids (SCs), continuously appear on the market and are booming due to their cannabis-like effect. New generation of smokable SCs, structurally dissimilar from Δ9-tetrahydrocannabinol (THC), have isomers with distinguishable pharmacokinetic parameters and therefore different in vivo effects. The isoforms are misidentified using conventional techniques such as gas or liquid chromatography coupled to mass spectrometry - or tandem mass - spectrometry. The aim of this study was to differentiate three positional isomers (JWH-007, JWH-019 and JWH-122) in single human hair samples, which store numerous substances revealing a way of life and consumption style. Matrix-assisted laser desorption/ionization (MALDI) combined with imaging is an innovative and powerful tool used since few years, especially in forensic research. Herein, we propose an innovative method to monitor the drugs of abuse consumption through direct mapping of the compounds with a high spatial distribution in human hair samples, by state-of-art imaging MALDI-MSⁿ. Three positional SC isomers (JWH-007, JWH-019 and JWH-122) were analysed using high and low fragmentation energy and the resulting MS/MS and even MS³ spectra differentiated the SCs. The MALDI-MS/MS and MS³ imaging was performed on hair soaked in a mixture of the three SCs as well as on hair from self-reported SC user, proving the potential of the technique for a forensic use. Keeping in mind that spatial distribution of organics from whole hair remains a challenge, the described methodology is a very promising analytical tool to probe the consumption of complex drugs and obtain correlation with its origin.