Direct nitrate sensing in water using an array of copper-microelectrodes from flat flexible cables

Nitrate determination plays a very important role in the analysis of environmental samples. In this paper, an activation procedure for nitrate sensing using a modified copper electrode made from flat flexible cables in presence of a low amount of chloride is reported. The proposed method exhibits enhanced electrocatalytic behaviour in the reduction of nitrate compared to a bare copper electrode. The proposed method showed linear response for nitrate in the concentration range 10-1070 μmol L−1, with a regression coefficient R2 = 0.999 (n = 12) and a limit of detection of 1.8 μmol L−1. According to the procedure based on the standard addition technique, the recovery values obtained were 93-103%, showing the accuracy of the proposed method. In addition, the proposed sensor was applied to the determination of nitrate in mineral water samples and the results are in good agreement (for a 95% confidence level according to the Student's t-test) with those obtained using the capillary electrophoresis procedure.