Poly(vinyl chloride) matrix membrane uranyl ion-selective electrodes based on organophosphorus sensors

Abstract

Uranyl ion-selective electrodes have been constructed from poly(vinyl chloride)(PVC) matrix membranes containing uranyl bis{di[4-(1,1,3,3-tetramethylbutyl)phenyl] phosphate} or uranyl bis(didecyl phosphate) as the electroactive component with dioctyl phenylphosphonate, tripentyl phosphate or tributyl phosphate as the plasticising solvent mediator. The electrodes were evaluated with particular regard to the speciation of uranium(VI) in solution. The most successful electrodes were based on the first uranyl bis salt, PVC and either dioctyl phenylphosphonate or tributyl phosphate solvent mediators. These systems gave slopes of 29 and 31 mV, respectively. None of the interferents examined (Fe³⁺, Fe²⁺, Ca²⁺, Zn²⁺, Mn²⁺, Cu²⁺ and Co²⁺) produced memory effects. The selectivity coefficients ranged from 9 × 10^–3 to 9 × 10^–4. The membranes withstood storage in the dry state for >10 months.