Functionalized Fe3O4 nanoparticles for electrochemical sensing of carbendazim

Functionalized magnetic nanoparticles (MNPs) can boost the performance of electrochemical sensors, increase their sensitivity, and modulate electrode-analyte interactions. In this work we used MNPs functionalized with poly(sodium acrylate) (Fe3O4@PAANa), trisodium citrate (Fe3O4@CIT) and branched polyethylenimine (Fe3O4@BPEI) to modify glassy carbon electrodes (GCE) towards the development of electrochemical sensors. Fe3O4@BPEI was selected to design an electrochemical sensor for carbendazim (CBZ) once this sample exhibited better performance in the enhancement of the electroactive area of GCE and decrease of the charge transfer resistance. Furthermore, we propose a pathway for the electrooxidation reaction of CBZ based on electrochemical measurements and the oxidation products detected by performing mass spectrometry. Our findings indicated that oxidation of CBZ occurs through the insertion of hydroxyl radicals and that the redox reaction involves the same number of protons and electrons. This electroanalytical methodology using Fe3O4@BPEI exhibited limit-of-detection and limit-of-quantitation values of 10 and 33 nmol L–1, respectively. Moreover, the proposed sensor exhibited high stability (%RSD = 1.31, n = 7), reproducibility (%RSD = 2.84, n = 5), and anti-interference ability. In addition, an electroanalytical methodology was successfully developed for the detection of CBZ in natural waters. This study presents the potential multidisciplinary application of functionalized MNPs as sensors for quantifying CBZ in natural waters and a likely reaction pathway for the electrochemical oxidation of CBZ.