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Determination of Nitrites in Water by In-electrode Coulometric Titration in Reticulated Vitreous Carbon Electrode

Katarina Lenghartova, Lukas Lauko, Frantisek Cacho, Ernest Beinrohr

Abstract


Nitrite in water samples was determined by in-electrode coulometric titration in a reticulated vitreous carbon (RVC) electrode of 100 ppi porosity. The sample was mixed with dilute sulphuric acid and sodium sulphate, filled into a flow cell with the porous electrode and nitrite was oxidised to nitrate by constant current of 5 µA at which the potential of the electrode was monitored. The limits of detection and quantification were found to be 0.4 and 1.2 µg/L, respectively. The repeatability and reproducibility were 2.2 % and 2.6 %, respectively. The bias at 100 µg/L were found to be 0.3 %. The duration of the measurement is 2-3 min depending on the nitrite concentration. There were few interferences only, neutral and cationic surfactants decreased and increased slightly the signal, respectively. Humic acids above 30 mg/L increased the signal by 10 %. Drinking and surface water samples were analysed and the results matched well those from the photometric method.

Keywords


Nitrite determination; drinking water; surface water; in-electrode coulometric titration; chronopotentiometry

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DOI: http://dx.doi.org/10.17344/acsi.2014.838

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Copyright (c) 2015 Katarina Lenghartova, Lukas Lauko, Frantisek Cacho, Ernest Beinrohr

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