Electrochemical determination of nitrites in natural waters with ultramicroelectrodes

This work reports the application of carbon-fiber and gold ultramicroelectrodes for the determination of nitrites in different media. The linear-sweep voltammetric response for nitrite oxidation on carbon fiber and gold was investigated in the anodic potential range up to 1.6 V (vs. the saturated calomel electrode). The experiments were performed in sulfate solutions, pure and natural waters. Natural water samples were obtained from a commercially available mineral water and from a heavily polluted urban creek. Very well-defined waves were always obtained showing a half-wave potential near to the value previously reported for NO oxidation. It was demonstrated that neither O2, or NO exert any influence in the nitrite oxidation response. The detection limits calculated were within the range of 2.6 to 9.7 μM, the highest being associated to the polluted water sample on carbon fiber and the lowest to mineral water on gold ultramicroelectrodes.

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