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-methyldihexylphosphine oxide O'-hexyl-2-ethylphosphoric acid (HL) incorporated into a poly(vinyl chloride) membrane were developed. This new derivative is proposed as a single molecular unit combining the overall properties of the synergistic single components, di-2-ethylhexylphosphoric acid and trioctylphosphine 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 2.0 x 10(-5) M, respectively. Results indicate a more effective interaction with the analyte in the case of having a unique molecule incorporating the two functional groups immobilized into a polymeric membrane, rather than the separated two synergistic ligands. Flow-through tubular electrodes based on both ionophores were also used as potentiometric detectors in flow injection techniques.

Chloride determination in serum by a flow-injection analysis precipitation pseudo-titration technique using a flow-through all-solid-state silver electrode.

A simply constructed, tubular, all-solid-state, flow-through silver electrode for flow-injection analysis (F.I.A.) is described. Use of a single line manifold accommodating the silver electrode, with a low level of silver ion (5 x 10(-4) M) in the carrier stream, is a useful method to determine chloride in serum, by means of a precipitation pseudo-titration F.I.A. technique. The sampling frequency is about 60/h.