Oxidative detection of nitrite at an electrocatalytic [Ru(bipy)2poly-(4-vinylpyridine)10Cl]Cl electrochemical sensor applied for the flow injection determination of nitrate using a Cu/Cd reductor column
✍ Scribed by Andrew P. Doherty; Margaret A. Stanley; Donal Leech; Johannes G. Vos
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 844 KB
- Volume
- 319
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
An electrochemical sensor developed from a redox polymer [Ru(bipy),(PVP),,Cl]Cl (where bipy is 2,2'-bipyridyl and PVP is poly-(4-vinylpyridine)) modified electrode for nitrite detection is described. The modified electrode acts as an efficient electrocatalyst for nitrite oxidation with amplification of electrode current by at least a factor of 3 compared with unmodified electrodes. The electrocatalytic reaction occurs throughout the polymer film in a three dimensional reaction zone and may be classified as an L, mechanism. The second order rate constant for the cross exchange reaction is 3.02 ( f 0.20) X 10' mol-' dm3 s-'. The sensor is applied to the determination of nitrate in a flow injection apparatus following the heterogeneous reduction of this species to nitrite at a copperised cadmium reductor column. The sensor exhibits a linear response range extending over three orders of magnitude from 1.0 X lo-' to 1.0 X 10m2 mol dmm3 nitrate with a limit of detection (signal-to-noise = 2) of 5.0 X lop6 mol dm-3. The coefficient of variation for measurement of 1.0 X 10m3 mol dm-' nitrite is 0.42% (n = 20). No passivation of the electrode surface was evident after over 200 repeat determinations. The system was applied to the determination of nitrate in commercial fertiliser compound.