Construction of an impedimetric immunosensor for label-free detecting carbofuran residual in agricultural and environmental samples

•Electrochemical impedance spectra analysis was for the first time employed to detect the small molecules of carbofuran.•The proposed method can be used in the detection carbofuran residual of real samples.•This analysis method is label-free with high sensitivity and selectivity.

In this paper, a label-free electrochemical impedance immunosensor for the detection of carbofuran was prepared by immobilizing l-cysteine on a gold electrode. The carbofuran antibodies were immobilized on the electrode by the using glutaraldehyde as a cross linker. The stepwise assembly of the electrode surface was confirmed by atomic force microscope (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under the optimized conditions, a linear relationship between the resistance change and the logarithm value of carbofuran concentration was obtained in the carbofuran concentration range of 1.0 × 10−1 - 1.0 × 103 ng/mL, with a detection limit of 1.0 × 10−1 ng/mL. The immunosensor performed good reproducibility and stability. Additionally, the proposed method can be applied for monitoring carbofuran residual in agricultural and environmental samples.