A. Florido et al., Uranyl-selective electrode based on a new bifunctional derivative combining the synergistic properties of phosphine oxide and ester of phosphoric acid, ANALYT CHEM, 72(7), 2000, pp. 1604-1610
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.