Gold nanoparticle decorated patronite on rGO for the quantification of sulfadiazine at nanomolar levels in contaminated water

Sulfadiazine (SDZ) contamination of the aquatic environment has been a critical concern in recent years due to its negative impacts on public health and ecological systems, and a reliable method is required to quantify it at ultra-low levels content in wastewater. We synthesized nanocomposite electrodes consisting of gold nanoparticles decorating VS₂-reduced graphene oxide sheets (AuNP/VS₂-rGO composites) on screen-printed carbon electrode (SPCE) using a facile hydrothermal method and used them for the in situ electrochemical quantification of SDZ at nanomolar levels in environmental water samples. Electrochemical impedance spectroscopy (EIS) results exhibited low resistance and high conductance on AuNP-VS₂-rGO/SPCEs (R_ct = 78 Ω). Under optimized conditions, the proposed sensor shows outstanding electrocatalytic performance ability to oxidize SDZ and produce significantly higher anodic peak currents than rGO/VS₂ or VS₂ composite. The AuNP-VS₂-rGO/SPCEs exhibited threshold concentration ranges between 10 and 345 nM and impressive sensitivity (0.1015 µA nM^-1cm⁻²) for the SDZ sensor. The detection limit for these electrodes was 0.44 nM, which meets requirements for environmental sample analysis. The produced AuNP-VS₂-rGO/SPCEs provided satisfactory reusability, stability, and anti-interference performance. Practically, these electrodes could be used to quantify SDZ and other toxic or hazardous pollutants in waste aqueous samples at nanomolar concentrations with acceptable recoveries.