Cai Xin, Xia Rui-Ze, Ye Jia-Jia, Huang Cong-Cong, Yang Yuan-Fan, Zhang Long-Ke, Liang Bo, Yang Meng, Lin Chu-Hong, Li Pei-Hua, Huang Xing-Jiu
Key Laboratory of Environmental Optics and Technology, and Environmental Materials and Pollution Control Laboratory, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei230031, China.
Department of Materials Science and Engineering, University of Science and Technology of China, Hefei230026, China.
Anal Chem. 2023 Feb 28;95(8):4104-4112. doi: 10.1021/acs.analchem.2c04935. Epub 2023 Jan 23.
Significant progress has been made in nanomaterial-modified electrodes for highly efficient electroanalysis of arsenic(III) (As(III)). However, the modifiers prepared using some physical methods may easily fall off, and active sites are not uniform, causing the potential instability of the modified electrode. This work first reports a promising practical strategy without any modifiers via utilizing only soluble Fe as a trigger to detect trace-level As(III) in natural water. This method reaches an actual detection limit of 1 ppb on bare glassy carbon electrodes and a sensitivity of 0.296 μA ppb with excellent stability. Kinetic simulations and experimental evidence confirm the codeposition mechanism that Fe is preferentially deposited as Fe, which are active sites to adsorb As(III) and H on the electrode surface. This facilitates the formation of AsH, which could further react with Fe to produce more As and Fe. Meanwhile, the produced Fe can also accelerate the efficient enrichment of As. Remarkably, the proposed sensing mechanism is a general rule for the electroanalysis of As(III) that is triggered by iron group ions (Fe, Fe, Co, and Ni). The interference analysis of coexisting ions (Cu, Zn, Al, Hg, Cd, Pb, SO, NO, Cl, and F) indicates that only Cu, Pb, and F showed inhibitory effects on As(III) due to the competition of active sites. Surprisingly, adding iron power effectively eliminates the interference of Cu in natural water, achieving a higher sensitivity for 1-15 ppb As(III) (0.487 μA ppb). This study provides effective solutions to overcome the potential instability of modified electrodes and offers a practical sensing platform for analyzing other heavy-metal anions.
在用于高效电分析砷（III）（As(III)）的纳米材料修饰电极方面已经取得了重大进展。然而，使用一些物理方法制备的修饰剂可能容易脱落，并且活性位点不均匀，导致修饰电极的电位不稳定。这项工作首次报道了一种有前景的实用策略，即仅利用可溶性铁作为触发剂，无需任何修饰剂来检测天然水中痕量水平的As(III)。该方法在裸玻碳电极上的实际检测限达到1 ppb，灵敏度为0.296 μA ppb，具有出色的稳定性。动力学模拟和实验证据证实了共沉积机制，即铁优先以铁的形式沉积，这些铁是电极表面吸附As(III)和氢的活性位点。这促进了AsH的形成，AsH可进一步与铁反应生成更多的砷和铁。同时，生成的铁也能加速砷的高效富集。值得注意的是，所提出的传感机制是铁族离子（Fe、Fe、Co和Ni）触发的As(III)电分析的一般规律。共存离子（Cu、Zn、Al、Hg、Cd、Pb、SO、NO、Cl和F）的干扰分析表明，由于活性位点的竞争，只有Cu、Pb和F对As(III)有抑制作用。令人惊讶的是，添加铁粉有效地消除了天然水中铜的干扰，实现了对1 - 15 ppb As(III)更高的灵敏度（0.487 μA ppb）。这项研究为克服修饰电极的潜在不稳定性提供了有效的解决方案，并为分析其他重金属阴离子提供了一个实用的传感平台。
