Contactless decontamination of hair samples: cannabinoids

Room temperature ionic liquids (ILs) have already been shown to provide efficient extraction media for several systems, and to capture volatile compounds, namely opiates. In this work, a novel, contactless, artefact-free extraction procedure for the removal of Δ⁹-tetrahrydrocannabinol (THC) from the surface of human hair is presented. To prepare in vitro cannabinoids-contaminated hair, samples were flushed with hashish smoke for 7 h. The decontamination experiments were carried at 100 °C for 24 h, according to the procedure previously described. Fifty-three ILs were screened and presented decontamination efficiencies ranging from 0 to 96 %. Although the majority of the ILs presented efficiencies above 90%, the 1-ethanol-3-methyl tetrafluoroborate (96%) was chosen for further process optimization. The Design of Experiments results demonstrated that all studied variables were significant for the process and the obtained optimum conditions were: 100 °C, 13 h and 175 mg of IL. In the work of Perrotin-Brunel et al. (J. Mol. Struct. 2011, 987, 67), it is demonstrated that, at 100 °C, full conversion of tetrahydrocannabinolic acid (THCA) into THC is obtained after 60 min. Since our decontamination takes place over 13 h at 100 °C, full conversion of THCA into THC is expected. Additionally, our method was compared with the method proposed by Cairns et al. (Forensic Sci. Int. 2004, 145, 97), through the analysis of 15 in vitro contaminated hair samples. The results demonstrated that with our method a mean extraction efficiency of 11 % higher was obtained.