An impedimetric immunosensor based on interdigitated microelectrodes (IDμE) for the determination of atrazine residues in food samples

A novel impedimetric immunosensor for atrazine detection has been developed. The immunosensor is based on an array of interdigitated μ-electrodes (IDμE) and immunoreagents specifically developed to detect this pesticide. Immunochemical determination of atrazine is possible without the use of any label. An atrazine-haptenized protein was covalently immobilized on the surface of the interdigitated μ-electrodes area (interdigits space) previously activated with (3-glycidoxypropyl)trimethoxysilane. Before, the gold electrodes were blocked using N-acetylcysteamine to prevent non-specific adsorptions. All biofunctionalization steps were characterized by chemical affinity methods and impedance spectroscopy. Immunosensors measures are made by exposing the sensor to solutions containing a mixture of the analyte and the specific antibody. With this configuration, the immunosensor detects atrazine with a limit of detection of 0.04 μg L^-1 without the use of any label. The potential of the immunosensor to analyze pesticide residues in complex sample matrices, such as red wine, has been evaluated. The results shown that after solid-phase extraction atrazine can be determined in this type of sample with a limit of detection of 0.19 μg L^-1, far below the Maximum Residue Level (MRL) established by EC for residues of this herbicide in wine.