Uranyl-selective electrode based on a new bifunctional derivative combining the synergistic properties of phosphine oxide and ester of phosphoric acid

Ion-selective electrodes based on the bifunctional chelating agent O-methyl dihexylphosphine oxide O'-hexyl-2-ethylphosphoric acid (HL) incorporated in to a poly(vinyl chloride) membrane were developed. This new derivative is p roposed as a single molecular unit combining the overall properties of the synergistic single components, di-2-ethylhexylphosphoric acid and trioctylp hosphine oxide. Two different ionophores, HL and its uranyl complex (UO2L2) , were studied. The response of the electrodes to uranyl ion was Nernstian for UO2L2 and super-Nernstian for HL ionophores, with detection limits of 3 .0 x 10(-6) and 3.0 x 10(-5) M, respectively. Results indicate a more effec tive interaction with the analyte in the case of having a unique molecule i ncorporating the two functional groups immobilized into a polymeric membran e, rather than the separated two synergistic ligands. Flow-through tubular electrodes based on both ionophores were also used as potentiometric detect ors in flow injection techniques.