Determination of Nitrate in Potable Water Using a Miniaturized Electrochemical Sensor

This paper presents the fabrication, characterization and application of a miniaturized electrochemical sensor for nitrate detection in potable water. The miniaturized sensor employed in the electrochemical measurements was fabricated by standard MEMS techniques. As the sensitive material, copper nanoparticles were prepared using electrodeposition method and characterized by scanning electron microscope. The electrodeposition process was completed with a controlled-potential reduction in acidic copper sulphate electrolyte directly. The electrocatalytic reduction of nitrate on copper surface under acidic condition (pH=2.0) was measured by linear sweep voltammetry (LSV) scan to implement the ion recognition and quantification process. The experimental results reveal that the deposited copper film was porous and exhibits a larger surface areas compared with average copper film. The sensor performed high sensitivity of 0.0332 mu A/mu molL(-1) for nitrate detection with the concentration range from 6.25 mu molL(-1) to 1000 mu molL(-1). Concentrations of five standard nitrate samples and two real water samples were measured. The results given by the sensors were in good agreement with the data obtained by standard ultraviolet (UV) spectrophotometric method for nitrate measurement. The maximum deviation between two methods is of 16.2%.