College of Science and Engineering, Flinders University, Bedford Park, South Australia, Australia.
College of Science and Engineering, Flinders University, Bedford Park, South Australia, Australia; Australian Federal Police, Canberra, Australian Capital Territory, Australia.
Forensic Sci Int. 2020 Sep;314:110389. doi: 10.1016/j.forsciint.2020.110389. Epub 2020 Jun 24.
Gunshot residue (GSR) is a valuable form of forensic trace evidence in the investigation of firearms crime. The current gold-standard approach does not include the analysis of organic components of the residues, which may be a deficiency, particularly in cases where there is little to no inorganic gunshot residue (IGSR) present or its attribution to a firearm source is ambiguous. A solvent extraction method was used for the extraction of organic GSR (OGSR) from the most common sampling device used to collect IGSR (i.e., SEM stubs with double-sided carbon adhesive tape). It was found that extraction did not significantly disturb inorganic GSR present on stubs, which raises the possibility that a valuable, comprehensive tandem analysis of both organic and inorganic GSR may be implemented using a single and commonly used residue collection device. The organic extract was analysed using Ultra High Performance Liquid Chromatography coupled to an Ion Trap Mass Spectrometer using Electrospray Ionisation (UHPLC-ESI-MS/MS), with preliminary results indicating that organic components can be extracted and detected at levels appropriate to casework GSR analysis. Testing of traces collected from the hands of recent shooters showed detection of stabiliser compounds typical of OGSR, which were confirmed to be present in the test ammunition's propellant. Total analysis time is approximately 30min per specimen, including preparation, instrumental analysis and data review. As the first step in the examination of GSR stubs in relation to a shooting case, extraction of organics and analysing them for the presence of OGSR may bring two operational benefits. First, that approach may be a useful way to determine which stubs warrant priority examination for IGSR, and second, it offers the possibility of providing relatively rapid case information to investigators.
射击残留物（GSR）是枪支犯罪调查中一种有价值的法医痕迹证据形式。目前的金标准方法不包括对残留物有机成分的分析，这可能是一个缺陷，尤其是在几乎没有无机射击残留物（IGSR）存在或其归因于枪支来源不明确的情况下。使用溶剂提取方法从最常见的用于收集 IGSR 的采样装置（即双面碳胶 SEM 短棒）中提取有机 GSR（OGSR）。结果发现，提取不会显著干扰短棒上存在的无机 GSR，这使得有可能使用单一且常用的残留收集装置对有机和无机 GSR 进行有价值的综合串联分析。使用电喷雾电离（UHPLC-ESI-MS/MS）对超高效液相色谱（UHPLC）进行有机提取物分析，初步结果表明可以提取和检测到适合案件 GSR 分析的有机成分水平。对最近射击者手部收集的痕迹进行测试，检测到 OGSR 典型的稳定剂化合物，这些化合物被确认为测试弹药推进剂中的存在。每个标本的总分析时间约为 30 分钟，包括准备、仪器分析和数据审查。作为射击案件中 GSR 短棒检查的第一步，提取有机物并分析其 OGSR 存在情况可能带来两个操作上的好处。首先，这种方法可能是确定哪些短棒需要优先检查 IGSR 的有用方法；其次，它提供了向调查人员提供相对快速的案件信息的可能性。
