McKeever Colm, Callan Sarah, Warren Susan, Dempsey Eithne
Department of Chemistry, Kathleen Lonsdale Institute for Human Health Research, Maynooth University, Maynooth, Co. Kildare, Ireland.
CREST Technology Gateway, FOCUS Research Institute, Technological University Dublin, Kevin St., Dublin, Ireland.
Talanta. 2022 Feb 1;238(Pt 2):123039. doi: 10.1016/j.talanta.2021.123039. Epub 2021 Nov 6.
The overall aim of the work was to advance electrochemical devices capable of analysis of forensically relevant residues using rapid electrochemical sensor technology. In order to achieve this, electrochemical detection of the propellant stabiliser diphenylamine (DPA) was achieved via voltammetry with signal enhancement realised in the presence of iron oxide nanoparticle modified transducers. This allowed both mechanistic and analytical evaluation with the aim to achieve the required selectivity and sensitivity for reliable detection. DPA electrochemistry was examined at glassy carbon electrodes in aqueous (3:7 methanol: sodium acetate pH 4.3) electrolyte via potential sweeping, with an irreversible wave at E = 0.67 V vs. Ag/AgCl. The diffusion coefficient (D) for the oxidation process was calculated as 1.43 × 10 cm s with αn = 0.7. DPA electrochemistry in a non aqueous methanol/acetonitrile electrolyte resulted in a D value of 5.47 × 10 cm s with αn = 0.5. Electrochemical preparation of magnetic iron oxide nanoparticles was achieved via electrooxidation of an iron anode in the presence of an amine surfactant followed by characterisation with SEM/EDX, XRD, FTIR and thermal analysis. A surface confined layer of these magnetic nanoparticles served to positively influence the response to DPA while impeding formation of surface confined oxidation products, with generation of an improved analytical signal - sensitivity 1.13× 10 A cm mM relative to bare electrode response (9.80 × 10 A cm mM) over the range 0.5-50 μM DPA using differential pulse voltammetry, with LOD 3.51 × 10 M and LOQ 1.17 × 10 M. Real sample analysis involved recovery and differential pulse voltammetry of unburnt and burnt gunshot residue with DPA qualitative and quantitative analysis.
这项工作的总体目标是利用快速电化学传感器技术开发能够分析法医相关残留物的电化学装置。为了实现这一目标，通过伏安法实现了推进剂稳定剂二苯胺（DPA）的电化学检测，在氧化铁纳米颗粒修饰的传感器存在下实现了信号增强。这使得能够进行机理和分析评估，以实现可靠检测所需的选择性和灵敏度。通过在玻碳电极上于水（3:7甲醇：醋酸钠pH 4.3）电解质中进行电位扫描来研究DPA的电化学，相对于Ag/AgCl，在E = 0.67 V处有一个不可逆波。氧化过程的扩散系数（D）计算为1.43×10 cm² s⁻¹，αn = 0.7。在非水甲醇/乙腈电解质中DPA的电化学导致D值为5.47×10 cm² s⁻¹，αn = 0.5。通过在胺类表面活性剂存在下对铁阳极进行电氧化来实现磁性氧化铁纳米颗粒的电化学制备，随后用扫描电子显微镜/能谱仪（SEM/EDX）、X射线衍射仪（XRD）、傅里叶变换红外光谱仪（FTIR）和热分析进行表征。这些磁性纳米颗粒的表面受限层有助于积极影响对DPA的响应，同时阻碍表面受限氧化产物的形成，使用差分脉冲伏安法在0.5 - 50 μM DPA范围内产生改进的分析信号 - 相对于裸电极响应（9.80×10⁻⁸ A cm⁻² mM⁻¹）灵敏度为1.13×10⁻⁷ A cm⁻² mM⁻¹，检测限（LOD）为3.51×10⁻⁸ M，定量限（LOQ）为1.17×10⁻⁷ M。实际样品分析包括对未燃烧和燃烧的枪击残留物进行回收率和差分脉冲伏安法分析以及DPA的定性和定量分析。
