Electrodeposition of redox materials with potential for enhanced visualisation of latent finger-marks on brass substrates and ammunition casings.

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry Pub Date : 2025-04-19 DOI:10.1016/j.forc.2025.100663

Colm McKeever, Eithne Dempsey

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Abstract

Electrochemical methods can play a key role in the analysis of impression evidence, specifically, latent finger-marks on brass substrates and ammunition casings, the latter being commonly encountered at crime scenes in forensic casework. In adopting such techniques, forensic investigators can potentially overcome some of the challenges associated with traditional visualisation methods, the use of aggressive reagents, preservation of evidence integrity and the need for extensive sample preparation. The spatially selective deposition of conducting/redox active polymers for visualising latent finger-marks on typically low-yield brass ammunition casings is examined here, exploiting the electrodeposition of 3,4-ethylenedioxythiophene (EDOT), together with a first-time study of phenozine vs. phenothiazine monomers, and their combinations at sheet and cartridge brass. Fine tuning of electrochemical protocols and conditions together with optimised monomer feedstocks played a key role in the finger-mark visualisation quality achieved with insights into brass electrochemistry. EDOT-thionine emerged consistently as the most effective combination upon electrochemical deposition on brass sheets, revealing latent finger-marks (groomed) at the highest level of detail (level 3), including pores within the papillary ridges, using a low energy, rapid (t = 120 s) constant potential (E_app = 0.1 V vs Ag|AgCl) approach. Successful visualisation of groomed and natural (donor) latent finger-marks was achieved following exposure of brass to temperatures of 700 °C and > 15-month room temperature aging. Bespoke electrochemical cells designed to facilitate the use of ammunition casings as working electrodes produced excellent results via potential sweeping, resulting in pristine visualised latent finger-marks (groomed) of grade 3 quality with visible level 3 (> 50 %) features.

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电沉积氧化还原材料，具有增强黄铜基材和弹壳上潜在手印可视化的潜力。

电化学方法可以在分析印痕证据中发挥关键作用，特别是黄铜基材和弹壳上的潜在手印，后者在法医案件工作中经常在犯罪现场遇到。在采用这种技术时，法医调查人员可以潜在地克服与传统可视化方法、使用攻击性试剂、保存证据完整性以及需要大量样品制备有关的一些挑战。本文研究了导电/氧化还原活性聚合物的空间选择性沉积，用于在典型的低产量黄铜弹壳上观察潜在的手印，利用3,4-乙烯二氧噻吩（EDOT）的电沉积，以及首次研究了吩嗪与吩噻嗪单体，以及它们在片材和弹壳黄铜上的组合。电化学方案和条件的微调以及优化的单体原料在通过对黄铜电化学的深入了解实现手指印可视化质量方面发挥了关键作用。edot -硫氨酸作为电化学沉积在黄铜片上最有效的组合，在最高细节水平（3级）上显示潜在的手印（修饰），包括乳头状脊内的孔隙，使用低能，快速（t = 120 s）恒定电位（Eapp = 0.1 V vs Ag|AgCl）方法。在将黄铜暴露于700°C和>的温度下后，成功地可视化了修剪过的和天然的（供体）潜在手印。室温陈酿15个月。定制的电化学电池设计便于使用弹药外壳作为工作电极，通过潜在扫描产生优异的效果，产生3级质量的原始可见潜在手印（修饰），可见3级(>；50%)特征。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Forensic Chemistry CHEMISTRY, ANALYTICAL-

CiteScore

5.70

自引率

14.80%

发文量

审稿时长

46 days

期刊介绍： Forensic Chemistry publishes high quality manuscripts focusing on the theory, research and application of any chemical science to forensic analysis. The scope of the journal includes fundamental advancements that result in a better understanding of the evidentiary significance derived from the physical and chemical analysis of materials. The scope of Forensic Chemistry will also include the application and or development of any molecular and atomic spectrochemical technique, electrochemical techniques, sensors, surface characterization techniques, mass spectrometry, nuclear magnetic resonance, chemometrics and statistics, and separation sciences (e.g. chromatography) that provide insight into the forensic analysis of materials. Evidential topics of interest to the journal include, but are not limited to, fingerprint analysis, drug analysis, ignitable liquid residue analysis, explosives detection and analysis, the characterization and comparison of trace evidence (glass, fibers, paints and polymers, tapes, soils and other materials), ink and paper analysis, gunshot residue analysis, synthetic pathways for drugs, toxicology and the analysis and chemistry associated with the components of fingermarks. The journal is particularly interested in receiving manuscripts that report advances in the forensic interpretation of chemical evidence. Technology Readiness Level: When submitting an article to Forensic Chemistry, all authors will be asked to self-assign a Technology Readiness Level (TRL) to their article. The purpose of the TRL system is to help readers understand the level of maturity of an idea or method, to help track the evolution of readiness of a given technique or method, and to help filter published articles by the expected ease of implementation in an operation setting within a crime lab.