Anodized screen-printed electrode modified with poly(5-amino-4H-1,2,4-triazole-3-thiol) film for ultrasensitive detection of Hg2+ in fish samples

Abstract

Anodized screen-printed electrode (ASPE) was modified by electrochemical polymerization of 5-amino-4H-1,2,4-triazole-3-thiol (ATT) to form a poly-ATT (PATT) film for the selective and sensitive detection of Hg2+ ions by Anodic Stripping Voltammetry (ASV). The porous PATT film was uniformly coated on the surface through disulfide (SS) linkage, free NH, and amide bonds for binding preconcentrated Hg2+ ions. The prepared PATT@ASPE was characterized by cyclic voltammetry, Field-Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM) with Energy Dispersive X-ray spectroscopy (EDS) and Attenuated Total Reflection Infrared Spectroscopy (ATR-IR). Under optimized experimental conditions (0.1 M KCl as supporting electrolyte and preconcentration at –0.1 V for 120 s), PATT@ASPE was successfully used for detecting Hg2+. A linear relationship between the anodic peak current and [Hg2+] was achieved in the concentration range of 0.03 to 245 nM, with a limit of detection (S/N = 3) of 0.005 nM and a calculated sensitivity of 15.0085 µAnM−1L-1 cm−2. Further, selective detection of Hg2+ was demonstrated in the presence of interfering species such as other heavy metal ions (Pb2+, Cd2+, Cu2+, etc.), organic molecules, other cations, and various anions. The electroanalytical performance of PATT@ASPE exhibited outstanding long-term stability and reproducibility. Finally, PATT@ASPE was successfully applied to measure Hg2+ in fish muscle samples, and the results were validated using inductively coupled plasma-mass spectrometry.