Department of Forensic Toxicology, Institute of Forensic Sciences, Ministry of Justice, Shanghai Key Laboratory of Forensic Medicine, Shanghai, 200063, PR China; Instrumental Analysis Center, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai, 200240, PR China.
Narcotics Control Commission, Nanjing Municipal Public Security Bureau, Nanjing, 210012, PR China.
Anal Chim Acta. 2017 Jul 4;975:42-51. doi: 10.1016/j.aca.2017.04.012. Epub 2017 Apr 10.
Segmental hair analysis offers a longer period for retrospective drug detection than blood or urine. Hair is a keratinous fiber and is strongly hydrophobic. The embedding of drugs in hydrophobic hair at low concentrations makes it difficult for extraction and detection with matrix-assisted laser desorption/ionization (MALDI) coupled with mass spectrometric imaging (MSI). In this study, a single scalp hair was longitudinally cut with a cryostat section to a length of 4 mm and fixed onto a stainless steel MALDI plate. Umbelliferone was used as a new hydrophobic matrix to enrich and assist the ionization efficiency of methamphetamine in the hair sample. MALDI-Fourier transform ion cyclotron resonance (FTICR)-MS profiling and imaging were performed for direct detection and mapping of methamphetamine on the longitudinal sections of the single hair sample in positive ion mode. Using MALDI-MSI, the distribution of methamphetamine was observed throughout five longitudinally sectioned hair samples from a drug abuser. The changes of methamphetamine were also semi-quantified by comparing the ratios of methamphetamine/internal standard (I.S). This method improves the detection sensitivity of target drugs embedded in a hair matrix for imaging with mass spectrometry. The method could provide a detection level of methamphetamine down to a nanogram per milligram incorporated into hair. The results were also compared with the conventional high performance liquid chromatography -tandem mass spectrometry (HPLC-MS/MS) method. Changes in the imaging results over time by the MSI method showed good semi-quantitative correlation to the results from the HPLC-MS/MS method. This study provides a powerful tool for drug abuse control and forensic medicine analysis in a narrow time frame, and a reduction in the sample amount required.
分段毛发分析提供了比血液或尿液更长的药物回溯检测时间。毛发是一种角蛋白纤维，具有很强的疏水性。药物以低浓度嵌入疏水性毛发中，使得用基质辅助激光解吸/电离（MALDI）与质谱成像（MSI）相结合进行提取和检测变得困难。在这项研究中，将单个头皮毛发用冷冻切片机纵向切成 4 毫米长，并固定在不锈钢 MALDI 板上。伞形酮被用作一种新的疏水性基质，以富集和提高毛发样品中甲苯丙胺的离子化效率。在正离子模式下，对单个毛发样品的纵向切片进行 MALDI-傅里叶变换离子回旋共振（FTICR）-MS 分析和成像，以直接检测和绘制甲 苯 丙 胺。使用 MALDI-MSI，观察到来自药物滥用者的五个纵向切片毛发样品中 甲 苯 丙 胺的分布。通过比较甲 苯 丙 胺/内标（IS）的比值，也对半定量了甲 苯 丙 胺的变化。该方法提高了质谱成像中嵌入毛发基质的目标药物的检测灵敏度。该方法可以将检测到的嵌入毛发中的甲 苯 丙 胺的含量下限降低到纳克/毫克。还将结果与传统的高效液相色谱-串联质谱（HPLC-MS/MS）方法进行了比较。MSI 方法随时间变化的成像结果与 HPLC-MS/MS 方法的结果具有良好的半定量相关性。这项研究为在短时间内进行药物滥用控制和法医分析提供了一种强大的工具，并减少了所需的样本量。
