Voltammetric detection of nitrate in water sample based on in situ copper-modified electrode

A simple and fast electroanalytical method for the detection of nitrate at an in situ copper-modified glassy carbon electrode (GCE) in an acidic media is proposed on the basis of square wave voltammetry. Since the fresh copper-modified electrode was formed in situ and the signals of nitrate were recorded in time, the whole experiment does not require sample preparation and oxygen removal from the solution degassed with nitrogen. Finally, a procedure for on-line electrochemical cleaning, the surface of GCE was employed to keep the copper film fresh. The whole experiment was rapid, in no more than 10 min. Under the optimal conditions, nitrates could be quantitatively determined in the range extending from 10 to 300 mu M, a very good linear correlation (R = 0.9996) can be observed when analyzing the relationship between the peak current and the ion concentration. In addition, the interferential effects of some common anions in water samples on the nitrate determination were also investigated. The results show that only nitrite ions could produce a distinct peak current at the same potential as nitrate does. When applying this method to detect nitrate in real water samples, the results exhibit good sensitivity. The procedure was also verified by the standard optical method.