Development of a sensitive nitrate-selective electrode for on-site use in fresh waters

Abstract

Twenty seven membranes hot pressed from mixtures of a variety of quaternary ammonium salt sensor molecules and mediators in Krynac polymer have been evaluated as nitrate-selective electrode membranes suitable for use in fresh waters. The best performance was obtained from a covalently bound triallyldecylammonium nitrate sensor having a Nernstian slope of –57.7 mV decade–1 over a nitrate range of 1 × 10–1 to 1.2 × 10–5 mol dm–3 NO3– with a limit of detection of 8.8 × 10–6 mol dm–3 NO3–.Membrane performance remained unchanged for at least six months use. Interfering ions, temperature and pH dependency studies are reported . Selectivity towards chloride at the 10–2 mol dm–3 level was measured as kpotNO3–,Cl– 1 × 10–4.