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.