Construction of MnO₂/ZnO/GCE Electrochemical Sensor and the Detection of Sulfamethoxazole in Honey

In order to rapidly detect sulfamethoxazole (SMZ) residues in honey, zinc oxide (ZnO) prepared by hydrothermal method and manganese dioxide (MnO₂) prepared by co-precipitation method were compounded on glassy carbon electrode (GCE) to construct MnO₂/ZnO/GCE electrochemical sensor for the detection of SMZ. The morphology and structure of the composites were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Differential pulse voltammetry (DPV) was used to explore the ratio and modification amount of the composite material to optimize the construction conditions of the sensor. DPV and cyclic voltammetry (CV) were used to investigate the detection conditions such as buffer solution pH and scanning rate. The results showed that when the mass ratio of m(ZnO):m(MnO₂) was 1:0.6, the addition amount of MnO₂/ZnO composite was 1.7×10⁻³ mg/mm², the pH was 8 and the scanning rate was 30 mV/s, the sensor had a good detection effect on SMZ. In the range of 0.3~100 μmol/L, the peak current of SMZ had a good linear relationship with the concentration, the linear equation was I_p=0.0843c+4.5168 (R²=0.9916), the limit of detection was 0.39 μmol/L and the limit of quantification was 1.30 μmol/L. The sensor was applied to the determination of honey sample, with a recovery of 95.5%~102.6% and a relative standard deviation (RSD) of 0.68%~2.55%. It shows that the sensor can realize the accurate detection of SMZ content. It has certain application value for the detection of SMZ residues in honey samples.