ELECTROCHEMICAL DETERMINATION OF NITRITES IN NATURAL-WATERS WITH ULTRAMICROELECTRODES

This work reports the application of carbon-fiber and gold ultramicroe lectrodes for the determination of nitrites in different media. The li near-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 i n sulfate solutions, pure and natural waters. Natural water samples we re obtained from a commercially available mineral water and from a hea vily polluted urban creek. Very well-defined waves were always obtaine d showing a half-wave potential near to the value previously reported for NO2- oxidation. It was demonstrated that neither O-2 or NO3- exert any influence in the nitrite oxidation response. The detection limits calculated were within the range of 2.6 to 9.7 mu M, the highest bein g associated to the polluted water sample on carbon fiber and the lowe st to mineral water on gold ultramicroelectrodes.