Practical Strategy for Arsenic(III) Electroanalysis without Modifier in Natural Water: Triggered by Iron Group Ions in Solution

Xin Cai; Rui-Ze Xia; Jia-Jia Ye; Cong-Cong Huang; Yuan-Fan Yang; Long-Ke Zhang; Bo Liang; Meng Yang; Chu-Hong Lin; Pei-Hua Li; Xing-Jiu Huang

doi:10.1021/acs.analchem.2c04935

Practical Strategy for Arsenic(III) Electroanalysis without Modifier in Natural Water: Triggered by Iron Group Ions in Solution

Anal Chem. 2023 Feb 28;95(8):4104-4112. doi: 10.1021/acs.analchem.2c04935. Epub 2023 Jan 23.

Authors

Xin Cai^{1

2}, Rui-Ze Xia³, Jia-Jia Ye⁴, Cong-Cong Huang^{1

2}, Yuan-Fan Yang^{1

2}, Long-Ke Zhang^{1

2}, Bo Liang^{1

2}, Meng Yang¹, Chu-Hong Lin⁵, Pei-Hua Li¹, Xing-Jiu Huang^{1

2}

Affiliations

¹ 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.
² Department of Materials Science and Engineering, University of Science and Technology of China, Hefei230026, China.
³ Institutes of Physical Science and Information Technology, Anhui University, Hefei230601, China.
⁴ Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei230026, China.
⁵ School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 62 Nanyang Drive, Singapore637459, Singapore.

PMID: 36688529
DOI: 10.1021/acs.analchem.2c04935

Abstract

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 Fe³⁺ 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^-1 with excellent stability. Kinetic simulations and experimental evidence confirm the codeposition mechanism that Fe³⁺ is preferentially deposited as Fe⁰, which are active sites to adsorb As(III) and H⁺ on the electrode surface. This facilitates the formation of AsH₃, which could further react with Fe²⁺ to produce more As⁰ and Fe⁰. Meanwhile, the produced Fe⁰ can also accelerate the efficient enrichment of As⁰. Remarkably, the proposed sensing mechanism is a general rule for the electroanalysis of As(III) that is triggered by iron group ions (Fe²⁺, Fe³⁺, Co²⁺, and Ni²⁺). The interference analysis of coexisting ions (Cu²⁺, Zn²⁺, Al³⁺, Hg²⁺, Cd²⁺, Pb²⁺, SO₄^2-, NO₃^-, Cl^-, and F^-) indicates that only Cu²⁺, Pb²⁺, and F^- showed inhibitory effects on As(III) due to the competition of active sites. Surprisingly, adding iron power effectively eliminates the interference of Cu²⁺ in natural water, achieving a higher sensitivity for 1-15 ppb As(III) (0.487 μA ppb^-1). 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.