Dual-Analyte Selective Electrochemical Detection of Phenylbutazone and Sulfamethoxazole Using Bio-Engineered BiS-ZnO Nanocomposites.

Simultaneous sensing and quantification of pharmaceutically active compounds (PhACs) are crucial for protecting the environment and maintaining long-term ecological sustainability. This study focuses on the bio-based synthesis of BiS-ZnO nanocomposites (BiS-ZnO(bio)) using bio-extract for dual-analyte selective and simultaneous electrochemical monitoring of phenylbutazone (PBZ) and sulfamethoxazole (SMZ) in the environmental matrices. BiS-ZnO(bio) exhibited ZnO(bio) nanostructures embedded on BiS(bio) nanorods with an average rod length of 1409.7 nm and a smaller crystal size of 14.43 nm. After immobilization of BiS-ZnO(bio) onto the glassy carbon electrode (BiS-ZnO(bio)/GCE), a 94.6% reduction in charge transfer resistance, a 63.2% rise in electroactive surface area, and a 76.5% enhancement in anodic peak response were observed than bare/GCE. The oxidation of PBZ and SMZ proceeded by releasing two electrons each, with a rate constant (k) of 0.907 s for PBZ and 0.721 s for SMZ. For simultaneous sensing, the BiS-ZnO(bio)/GCE achieved the limit of detections (LODs) of 0.222 and 0.089 μM with sensitivities of 0.116 and 0.296 μA μM cm for PBZ and SMZ, respectively, within a linear range of 0.25-120 μM. The presence of interference could not interfere with the electrochemical sensing of PBZ and SMZ, and only a decrease in peak response of 12.9% for PBZ and 11.8% for SMZ was observed after 10 reuse cycles during the simultaneous sensing. The developed simultaneous sensing platform could efficiently detect and quantify PBZ and SMZ in real water samples, achieving about 100% recovery.