José Restolho

Development, optimization, and validation of a novel extraction procedure for the removal of opiates from human hair's surface.

Room temperature ionic liquids (ILs) have proved to be efficient extraction media for several systems, and their ability to capture volatile compounds from the atmosphere is well established. We report herein a contactless extraction procedure for the removal of opiate drugs from the surface of human hair. The compounds were chosen as a model drug, particularly due to their low volatility. Equal amounts of IL and hair (about 100 mg) were introduced in a customized Y-shaped vial, and the process occurred simply by heating. After testing several ILs, some of them (e.g. 1-methyl-3-ethanol-imidazolium tetrafluoroborate, phenyl-trimethyl-ammonium triflate or bis(dimethyl) diheptylguanidinium iodide) showed extraction efficiencies higher than 80% for the two studied compounds, morphine and 6-monoacetylmorphine. Using the design of experiments (DOE) approach as an optimization tool, and bearing in mind the hygroscopic properties of the ILs (in particular, 1-methyl-3-ethanol-imidazolium tetrafluoroborate), the process was optimized concerning the following variables: temperature (50-120 ºC), extraction time (8-24 h), IL amount (50-200 mg) and water content of the IL (0.01-60%). This study not only provided the optimum conditions for the process (120 ºC, 16 h, 100 mg of IL containing 40% of water), but has also showed that the water content of the IL represents the variable with the most significant effect on the extraction efficiency. Finally, we validated our method through the comparison of the results obtained by treating hair samples with the described procedure to those obtained using a standard washing method and criteria for positivity.

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. Copyright

Response to the letter to the editor Reply to Restolho et al. "Contactless decontamination of hair samples: cannabinoids" by Moosmann and Auwärter.

First of all, we would like to thank Drs Moosmann and Auwärter for their interest in our paper, which describes a new approach for hair decontamination prior to cannabinoids analysis. Although we feel that scientific discussion regarding published work is valuable, there were somemisunderstandings and incorrect assumptions concerning their interpretation of our work, which we aim to clarify in this letter. In the letter from Moosmann and Auwärter, they refer to a comment on their work made in the introduction of our paper. Our comment on the controversy regarding their paper reflects mainly our opinion, since we believe that their assumption concerning the lack of THC incorporation via the bloodstream is polemic and susceptible of generating some controversy between hair analysts. Our comment may, in fact, be misleading to the reader, since to our knowledge, there is no ongoing scientific discussion regarding that particular paper. However, we do not feel that our comment questions the validity of those authors’ study, in the sense that they apparently have interpreted our words. Concerning THC incorporation via the bloodstream, the authors claim, in their study, that ‘[...] no relevant incorporation through the bloodstream into hair is expected to occur in cannabis users...’, concluding in the same sentence that ‘[...] THC detected in forensic hair samples does originate from external sources.’ It is our opinion that their study with only two subjects lacks statistical significance and does not allow to draw the referred conclusion. Please note that we feel the same about our study (we have stated it in the manuscript), and we have used 15 subjects. Nevertheless, we want to stress that the study of Moosmann and Auwärter was not part of the scope of our manuscript. Regarding THC’s pKa, indeed phenolic groups can have acidic properties, but they can also behave as weak bases. Therefore, it is our opinion that THC will behavemore like a base or, at most, like a weak base. Additionally, in the study of Nakahara et al., they state that the incorporation rate will depend on several factors, i.e., pH gradient, lipophilicity, and melanin interactions. Another interesting aspect of this study is that, in the case of THCCOOH, despite being much more acidic than THC, it is also incorporated into the growing hair follicle. The assessment of the protein interaction of the drug was not performed because it was not included in the aim of the study. In Moosmann and Auwärter’s letter, the need of more effective decontamination process is questioned, though we do not share their opinion. As we state in the introduction of our paper: ‘to detect THCCOOH more sensitive techniques are needed (e.g. gas chromatography-tandem mass spectrometry (GC-MS/MS), which are quite expensive and not available in most laboratories. It is also possible to find several publications where the authors have failed to detect THCCOOH in positive hair samples, even using highly sensitive instrumentation. ’ The authors disagree with our contamination method and the ‘unrealistic’ THC concentrations obtained. We understand their point, and that is why we commented on this issue in our paper using the exact same words, in the Results and Discussion section:

Capture of Opiates by Ionic Liquids

Room temperature ionic liquids (RTILs) are known to provide efficient extraction media for a variety of systems. In particular, their ability to remove low volatility compounds (including opiate drugs) from the surface of human hair was recently demonstrated by this team. Among many tested ILs, some exhibited high extraction efficiencies for the two studied compounds, morphine and 6-monoacetylmorphine, while others have practically zero efficiency. The aim of the present study was to further understand the special affinity of specific combinations cation/anion towards the opiate drugs, through a systematic study of a limited number of ILs: 1-ethyl-3-methylimidazolium acetate, [C2mim][OAc], 1-butyl-3-methylimidazolium acetate [C4mim][OAc], 1-hexyl-3-methylimidazolium acetate [C6mim][OAc], 1-ethanol-3-methylimidazolium tetrafluoroborate, [C2OHmim][BF4], 1-ethanol-3-methylimidazolium chloride [C2OHmim][Cl], and 1-butyl-3-methylimidazolium tetrafluoroborate, [C4mim][BF4]. Correlations between the efficiency of drug extraction from hair and the water content, surface tension and polarity of the ionic liquids (ILs) were found. The extraction efficiency increased with the IL’s water content, although in a different way for each IL/drug pair. A decrease in the surface tension during the process of drug extraction was detected only for highly efficient ILs. Efficiency was correlated with the polarity parameters defined by Kamlet and Taft: large for ILs of high acidity and low basicity (e.g. [C2OHmim][BF4]) and small for liquids with of low acidity and high basicity (e.g. [C6mim][OAc]).