Flow injection amperometric determination of nitrite at a carbon fibre electrode modified with the polymer [Os(bipy)2(PVP)20Cl]Cl

Abstract

The development of carbon fibre electrodes modified with the polymer [Os(bipy)₂(PVP)₂₀Cl]Cl for the flow amperometric determination of nitrite is described. This osmium polymer modifier greatly enhances the kinetics of nitrite reduction compared with the reaction at bare carbon electrodes. Various electrode characteristics were optimized using both cyclic voltammetry and flow injection. The calibration graph yielded a slope of 0.197 nA cm³µg^–1 over the linear range 0–400 µg cm^–3 with a limit of detection of 0.1 µg cm^–3. The modified electrode was shown to exhibit good short-term reproducibility yielding a relative standard deviation of 2.15%(n= 20). After a 3 week period of monitoring, involving 240 standard injections and 30 meat extract injections, the electrode continued to function with no significant change in sensitivity. The electrode was used to analyse a processed meat sample for nitrite content and the results compared favourably with those obtained using a standard reference spectrophotometric method.