Capabilities of laser ablation—inductively coupled plasma mass spectrometry for (trace) element analysis of car paints for forensic purposes
Capabilities of laser ablation—inductively coupled plasma mass spectrometry for (trace) element analysis of car paints for forensic purposes
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激光烧蚀的能力 - 电感耦合等离子体质谱法用于法医学目的汽车油漆（痕量）元素分析
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发表时间：
2006
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通讯作者：
F. Vanhaecke
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作者：
Isolde Deconinck;C. Latkoczy;D. Günther;F. Govaert;F. Vanhaecke
激光烧蚀电感耦合等离子体质谱（LA-ICP-MS）的深度剖析分析的汽车油漆的能力进行了探讨，从而获得的信号配置文件的使用法医鉴定的车辆肇事逃逸事故的评价。对汽车油漆样品的深度剖析分析提供了关于各层（透明涂层、底涂层、底漆和第一道底漆）的元素组成的详细信息。然而，已经确定，当使用基于四极杆的ICP-MS仪器时，某些层的复杂基质组成-有机组分和高浓度的无机化合物，例如高岭土，（Al2O3.2SiO2.2H2O）、滑石（3 MgO·4SiO 2·H2O）、重晶石（BaSO 4）和/或含铁颜料-导致光谱干扰，显著影响特别是对于过渡金属获得的信号分布。实验确定的同位素比从相应的真实值的偏差进行了评估，作为一个非常有用的指示光谱重叠。应用电感耦合等离子体扇形场质谱仪（ICP-SF-MS），在中等质量分辨率（R = 4000），允许大多数干扰离子被识别和记录，主要是根据其确切的质荷比。在犯罪现场发现的汽车油漆碎片通常非常小，因此必须最大限度地利用LA-ICP-MS的多元素能力，允许测量尽可能多的分析物，以便于明确区分各种油漆来源。因此，高质量分辨率被评估为克服上述光谱重叠的最佳可能方式。通过LA-ICP-MS获得的信号分布允许相同颜色的汽车油漆根据各个层的元素组成相互区分。使用目标元素的信号强度与Ti的信号强度之比，Ti以高浓度存在于底漆表面处理剂和所有汽车油漆样品中的第一底漆中，建议作为定量结果的第一步，至少对于这两层。
The capabilities of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for depth profiling analysis of car paints were explored and the use of the signal profiles thus obtained for forensic purposes—identification of the vehicle involved in a hit-and-run accident—evaluated. Depth profiling analysis of car paint samples provided detailed information on the elemental composition of the individual layers (clear coat, base coat, primer surfacer and first primer). It was, however, established that when using a quadrupole-based ICP-MS instrument, the complex matrix composition of some of the layers—organic components and high concentrations of inorganic compounds, such as kaolin (Al2O3.2SiO2.2H2O), talc (3MgO.4SiO2.H2O), barite (BaSO4) and/or Fe-containing pigments—resulted in spectral interferences, significantly affecting the signal profiles obtained especially for the transition metals. Deviation of experimentally determined isotope ratios from the corresponding true values was assessed as a very useful indication of spectral overlap. Application of an inductively coupled plasma sector field-based mass spectrometer (ICP-SF-MS), operated at medium mass resolution (R = 4000), permitted most interfering ions to be identified and documented, primarily on the basis of their exact mass-to-charge ratio. Car paint fragments found at crime scenes are usually very small, such that the multi-element capabilities of LA-ICP-MS have to be exploited to the largest possible extent, allowing the measurement of as many analytes as possible, facilitating clear differentiation of the various paint sources. High mass resolution was therefore assessed as the best possible way to overcome the aforementioned spectral overlap. The signal profiles obtained via LA-ICP-MS permitted car paints of the same colour to be discriminated from one another on the basis of the elemental composition of the individual layers. Using the ratio of the signal intensity for the target elements to that of Ti—present at high concentration in the primer surfacer and the first primer in all of the car paint samples investigated—is suggested as a first step towards quantitative results, at least for these two layers.