Development of Molecularly Imprinted Surface Plasmon Resonance Sensor for the Detection of Metrafenone at Maximum Residue Levels

In this study, metrafenone (MET), a widely used pesticide, was detected in food, soil, and water samples using a molecularly imprinted surface plasmon resonance (MIP@SPR) sensor. For this purpose, MET-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-L-phenylalanine methyl ester) (MET-MIP) nanoparticles were synthesized and immobilized onto the surface of SPR sensors, thereby creating MET-specific recognition sites. The characterization of MET-MIP nanoparticles was performed using Nano Zetasizer measurements and scanning electron microscopy (SEM). The surface characterization of the MIP@SPR sensors was conducted using atomic force microscopy (AFM), contact angle measurements, and Fourier-transform infrared (FTIR) spectroscopy with attenuated total reflectance (ATR) analysis. Kinetic analyses were performed using the SPR system with MET solutions prepared in the concentration range of 0.01–10 mg/L. The obtained results indicated that the limit of detection (LOD) of the MIP@SPR sensor for MET detection was 0.0031 mg/L. For selectivity studies, novaluron was used as the competitor molecule. The MIP@SPR sensors exhibited a 19.92-fold higher selectivity for MET than for novaluron. To evaluate the success of the imprinting process, non-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-L-phenylalanine methyl ester) (NIP) nanoparticles were synthesized, and the imprinting factor of the MIP@SPR sensor was calculated as 17.78. For real sample analysis, tomato samples were tested using the MIP@SPR sensor, and high-performance liquid chromatography (HPLC) analysis was conducted to confirm the presence of MET in the tomato samples, thereby validating the results.