Application of polypyrrole-based selective electrodes in electrochemical impedance spectroscopy to determine nitrate concentration

Nitrate is a commonly found nitrogen species in the environment, especially in agricultural regions. Since excessive nitrate accumulation has negative impacts on the environment, the quantitative monitoring of nitrate levels in the field is a critical component of precision agriculture. Researchers recently showed the application of plasticized polyvinyl chloride electrodes in conjunction with electrochemical impedance spectroscopy (EIS) to monitor nitrate levels. In this paper, we show that nitrate doped polypyrrole (PPy(NO
₃
^-
)) electrodes (which have a simpler fabrication) also have the potential of serving as nitrate sensors in EIS applications. To the knowledge of the authors, PPy(NO
₃
^-
) electrodes have not been used before to monitor nitrate levels using EIS. Using a metric extracted from the low-frequency EIS behavior of our PPy(NO
₃
^-
) electrodes, we also show the potential of realizing a nitrate sensor whose output response spans ~100X for an input dosage range of 30ppm-6200ppm. This may lead to the future development of low-power and responsive nitrate sensors for large-scale field deployment.