Ong Ta-Hsuan, Ljunggren James, Mendum Ted, Geurtsen Geoff, Kunz Roderick Russell
Biological & Chemical Technologies, Massachusetts Institute of Technology Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02421, United States.
Charlie Four Security Group, 33 Santom Street, Auburn, Massachusetts 01501, United States.
ACS Omega. 2022 Jun 17;7(26):22567-22576. doi: 10.1021/acsomega.2c01882. eCollection 2022 Jul 5.
Non-intrusive means to detect concealed firearms based on magnetometry are widely accepted and employed worldwide. Explosive detection canines can also detect concealed firearms provided that they are imprinted on materials that may be related to firearms such as nitroglycerin in double-base smokeless powders. However, there are hundreds of possible smokeless powder formulations across various manufacturers, presenting a challenge for trained canines to generalize across all possible powder compositions. In response, this paper reports a set of potential imprinting vapor(s) that may help detection canines generalize across a variety of double-base smokeless powders and gunshot residues. Statistical analysis was conducted on the smokeless powder database maintained by the National Center for Forensic Science, and headspace measurements targeting nitroglycerin and diphenylamine were collected from several powders. In addition, measurements were taken to track nitroglycerin and diphenylamine vapor concentration changes over time on the spent casings and gun barrels of four types of ammunition. The observed vapor concentration mixing ratios for nitroglycerin and diphenylamine from residues were in the part-per-billion to part-per-trillion range, which would be challenging to detect for many field-deployed explosive vapor detectors and indicate continued importance of canines for forensic investigation and crime prevention. Analyses suggest four potential vapor compositions for imprinting. For unburnt powders, 90% nitroglycerin and 10% diphenylamine appear adequate for most powders, and 90% dinitrotoluene and 10% diphenylamine is a possible candidate to increase generalization to powders that contain dinitrotoluene instead of nitroglycerin. 100% nitroglycerin appears adequate for many gunshot residues (GSRs). Diphenylamine may be present in some GSRs, and equal compositions of nitroglycerin and diphenylamine may be adequate for imprinting against these residues as they age (this study tracked signatures up to 7 weeks after discharge).
基于磁力检测隐藏枪支的非侵入性方法在全球范围内被广泛接受和应用。爆炸物探测犬也能够检测隐藏的枪支，前提是枪支印刻在可能与枪支有关的物质上，比如双基无烟火药中的硝化甘油。然而，不同制造商生产的无烟火药配方可能有数百种之多，这给经过训练的探测犬识别所有可能的火药成分带来了挑战。针对这一问题，本文报告了一组潜在的印记挥发物，它们可能有助于探测犬识别各种双基无烟火药和枪击残留物。我们对国家法医学中心维护的无烟火药数据库进行了统计分析，并从几种火药中收集了针对硝化甘油和二苯胺的顶空测量数据。此外，我们还进行了测量，以跟踪四种弹药的用过弹壳和枪管上硝化甘油和二苯胺蒸汽浓度随时间的变化。从残留物中观察到的硝化甘油和二苯胺蒸汽浓度混合比在十亿分之一到万亿分之一的范围内，这对于许多现场部署的爆炸物蒸汽探测器来说很难检测到，这也表明了探测犬在法医调查和犯罪预防中的持续重要性。分析表明有四种潜在的用于印记的蒸汽成分。对于未燃烧的火药，90%的硝化甘油和10%的二苯胺似乎适用于大多数火药，90%的二硝基甲苯和10%的二苯胺可能是一个备选方案，以提高对含二硝基甲苯而非硝化甘油的火药的识别能力。100%的硝化甘油似乎适用于许多枪击残留物（GSR）。二苯胺可能存在于一些枪击残留物中，随着残留物老化，等量的硝化甘油和二苯胺成分可能适用于对这些残留物进行印记（本研究跟踪了射击后长达7周的特征）。
