Manganese-doped zinc sulfide microspheres for improved electrocatalytic sensing ability toward carbendazim in food samples

The fungicide carbendazim (CBZ) is generally used to make crops more resistant to pathogens. However, because pesticide residues due to overuse have polluted food products, they have become a global public health problem. Ultralow-level determination of CBZ in food products has become crucial for health protection and environmental safety; however, the task remains challenging. In this study, a composite containing Mn-doped ZnS was prepared with a facile reflux approach. Compared with conventional ZnS electrodes and GCEs, the hierarchical Mn-doped ZnS microspheres with abundant edge/defect sites improve the interface charge transfer capacity, thereby resulting in a lower R_ct. The Mn-doped ZnS-GCE displays excellent electrocatalytic sensing ability for CBZ in 0.05 M PBS at a higher anodic current and low sensing potential compared to those of other ZnS electrodes and GCEs. The square wave voltammetry (SWV) results confirm that the Mn-doped ZnS-GCE has a more comprehensive linear working range (5–120 nM) for CBZ, and the measured ultralow detection limit for CBZ is 0.03 nM. Interestingly, we investigated the real-time applicability of the Mn-doped ZnS-GCE for the precise identification of spiked CBZ in lemon wash water samples, tomato sauce, and orange juice samples with satisfactory recovery.