Electrodeposition of Copper Nano-clusters at a Platinum Microelectrode for Nitrate Determination

A method based on cyclic voltammetry to modify the sensing surface to be macroporous copper nano-clusters was developed and for the detection of nitrate in a micro amperometric electrode, which was an electrochemical system composed of two-electrode system and fabricated based on Micro-Electro-Mechanical Systems (MEMS) technology. The experiment results demonstrate that this method as a controllable and convenient manipulation can effectively modify the surface of the working electrode for further nitrate determination more rapidly with less consumption of reagent, and enhance the sensitivity of the electrode. The experimental results reveal that under the optimal experimental conditions microelectrode surface modified by cyclic voltammetry electrodeposition was macroporous and had a larger effective surface area, which shows marked sensitivity and selectivity for nitrate ions within the concentration range from 6.25 to 3500 mu mol/L (6.25-300 mu mol/L yielded straight lines: y(1) = -0.0526x-3.905, R-1(2) = 0.9993, while in the range of 300-3500 mu mol/L yielded straight lines; y(2) = -0.0353x-13.653, R-2(2) = 0.9918). Interference analysis with 9 kinds of ions (NO2, Cl, HPO42-/PO43-, SO42-, HCO3-/CO32-, Na+ and K+) commonly found in groundwater indicates that only NO2- cause reasonable interference. These electrodes were applied to detect nitrate concentration in water samples from lake and river. The test results using these microelectrodes was consistent with the concentration given in the certificate of qualified water quality detection institute. This work is potential to develop a portable, cost-effective and accurate microsensor for real-time sensing of nitrate ions.