Bipyridine-functionalized covalent-organic-framework-modified screen-printed electrode for ultrasensitive electrochemical determination of arsenic (III)

The high toxicity of the arsenic ion (As3+) and its proliferation as a contaminant make it a significant threat to the environment as well as to human beings. Therefore, recent years have witnessed the development of novel strategies for the ultrasensitive detection of As3+. In this study, we design a covalent organic framework (COF) to modify a screen-printed electrode for the ultrasensitive electrochemical determination of As3+ via square wave anodic stripping voltammetry (SWASV). As a proof of concept, we propose a novel bipyridine-containing COF, namely BPTB, which is a screen-printed electrode modification material with a large Brunauer–Emmett–Teller (BET) surface area, high selectivity, and good anti-interference properties. The extremely selective As3+ receptors are the nitrogen-based sites, and the bipyridine-group skeleton serves as a signal transducer. The COF-modified screen-printed electrode exhibits an ultralow detection limit of 38.09 nmol/L and a wide linear response range of 0.1–80 μmol/L for As3+ determination under optimal conditions. In addition, the electrochemical properties of the COF-modified screen-printed electrode are characterized via cyclic voltammetry and electrochemical impedance spectroscopy. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis confirms the existence of a strong interaction between the bipyridine sites of BPTB and As3+, which influences the stripping current intensity of the modified screen-printed electrode. In summary, this study not only highlights the application potential of COFs for the electrochemical determination of As3+ but also demonstrates a novel, convenient approach for constructing COFs by creatively introducing chelating sites for toxic metals.