Single frequency impedimetric immunosensor for atrazine detection

A novel impedimetric immunosensor for the detection of a wide variety of compounds, based on a two coplanar non-passivated interdigitated metallic μ-electrodes and non-labeled immunoreactives, has been designed and developed. A very useful detection method is the impedance spectroscopy sweeping a wide frequency range. This is a powerful, but cumbersome tool to study the sensor performance providing trustworthy results. In this work, it is shown that the exploitation of the changes observed of the impedance at a single frequency provide very good correlation with antibody concentration and hence greatly reduces the signal acquisition and processing complexity. It has thereby a great potential for low cost, low power, fast response and simple use for the in-field or at-line applications. In this work, the application of the method to atrazine detection is described. The results show that the immunosensor signal is a function of the pesticide concentration following a competitive binding relationship, with limits of detection lower than the maximum residue level required by EC for atrazine in wine grapes and other foodstuff products.