Department of Forensic Pharmacology & Toxicology , Zurich Institute of Forensic Medicine (ZIFM), University of Zurich , Winterthurerstrasse 190/52 , CH-8057 Zurich , Switzerland.
Laboratory for Nanoscale Materials Science, Empa , Ueberlandstrasse 129 , CH-8600 Duebendorf , Switzerland.
Anal Chem. 2019 Mar 19;91(6):4132-4139. doi: 10.1021/acs.analchem.8b05866. Epub 2019 Mar 7.
Contamination is a highly controversial issue in hair analysis. Therefore, hair testing protocols typically include wash steps to remove contamination. However, recent studies claim that washing could also lead to permanent incorporation of contaminants into hair, thus questioning the validity of hair testing at all. In the present study, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with longitudinal sectioning of single hairs and different decontamination protocols was used to reveal differences between the incorporation of a substance into hair from external sources and an incorporation via bloodstream. Single hairs were longitudinally sectioned using a custom-made sample holder. Data were acquired with MALDI-MS by rastering each hair individually. Single hair samples from drug users, blank hairs, and zolpidem- and zolpidem-D6-soaked hairs were investigated. Different published washing protocols were tested, and an in-house washing protocol was developed. For images with higher spatial resolution, time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used. Longitudinal sectioning of hairs dramatically increased sensitivity; even single-dose administrations of zolpidem in single hairs could thus be detected using MALDI-MS. Zolpidem from external sources could be detected in large quantities in superficial hair structures. Zolpidem from consumer hairs, proposed to be strongly bound to inner hair structures, could not be completely removed even by the strongest tested decontamination protocol, whereas zolpidem-soaked hairs could be cleared almost completely with the developed in-house wash protocol. The applied methods allowed a first insight into the connection of decontamination protocols and wash-in phenomena in hair analysis. Further studies with other drugs are necessary to assess the general validity of these findings.
污染是头发分析中一个极具争议的问题。因此，头发检测方案通常包括清洗步骤以去除污染物。然而，最近的研究声称，清洗也可能导致污染物永久地掺入头发中，从而对所有头发检测的有效性提出质疑。在本研究中，使用基质辅助激光解吸/电离质谱（MALDI-MS）对单根头发进行纵向切片和不同的去污方案，以揭示从外部来源将物质掺入头发中和通过血液途径掺入头发之间的差异。使用定制的样品架对单根头发进行纵向切片。通过单独对每个头发进行光栅扫描，使用 MALDI-MS 采集数据。研究了来自吸毒者、空白头发和唑吡坦和唑吡坦-D6 浸泡头发的单根头发样本。测试了不同已发表的清洗方案，并开发了内部清洗方案。对于具有更高空间分辨率的图像，使用飞行时间二次离子质谱（ToF-SIMS）。头发的纵向切片大大提高了灵敏度；因此，即使在单根头发中单次给予唑吡坦，也可以使用 MALDI-MS 检测到。可以在表面头发结构中大量检测到来自外部来源的唑吡坦。从消费者头发中提出的与内部头发结构强烈结合的唑吡坦即使经过最强的测试去污方案也不能完全去除，而浸泡唑吡坦的头发可以用开发的内部清洗方案几乎完全清除。应用的方法使我们首次深入了解了头发分析中去污方案和清洗现象的联系。需要对其他药物进行进一步研究，以评估这些发现的普遍有效性。
