Hybrid chitosan-coated manganese ferrite nanoparticles for electrochemical sensing of bifenox herbicide

Abstract A novel glassy carbon electrode (GCE) modified with hybrid chitosan-coated manganese ferrite nanoparticles (MnFe2O4@CTS) was applied for the electrochemical determination of bifenox, which is a nitrodiphenyl ether herbicide. The core-shell MnFe2O4@CTS nanoparticles were synthesized via ionic gelation and characterized by different techniques including transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and thermogravimetric analysis. The modification of the GCE was performed by drop-casting method using MnFe2O4@CTS, previously dispersed by ultrasound. For the first time, the synthesized material was tested in the electroanalysis of environmental pollutants. The innovative modified MnFe2O4@CTS/GCE provided a significant increase of peak currents in the presence of bifenox. Electrochemical and interfacial characteristics of the electrodes were assessed by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimized conditions of square wave voltammetry and supporting electrolyte, it was possible to observe a linear dependence between the anodic peak current and the concentration of bifenox in the range from 0.3 to 4.4 μmol L−1. The limit of detection was estimated as 0.09 µmol L−1. The selectivity of the sensor was verified in the presence of other pesticides and the river water matrix; the interference response was found to be lower than 5%. The sensor showed excellent intra-day and inter-day repeatability presenting a relative standard deviation of 3.99% and 5.79%, respectively. Electrochemical determination of bifenox was performed in river and tap water samples. The recovery values were in the range of 82–97%. The novel analytical platform MnFe2O4@CTS/GCE presented promising features for application in environmental analysis of bifenox.