Determination of nitrate in mineral water and sausage samples by using a renewable in situ copper modified electrode

A new approach for in situ electrodeposition of a renewable copper layer onto a copper electrode is reported. The active surface was obtained by anodic dissolution of a copper electrode at an appropriate potential and further redeposition of copper ions still remaining at the diffusion layer. Under optimal experimental conditions the peak current response increases linearly with nitrate concentration over a range of 0.1-2.5 mmol L⁻¹. The repeatability of measurements for nitrate was evaluated as 1.8% (N = 15) and the limit of detection of the method was found to be 11 μmol L⁻¹ (S/N = 3). Nitrate contents in two different samples (mineral water and sausages) compared well with those obtained from using the standard Griess protocol at a 95% of confidence level measured by the t-student test. The interference from chloride on the nitrate analysis and the possibility of simultaneous determination of nitrite were also examined.