Fluorimetric determination of europium over a large dynamic range using its ternary complex with thenoyltrifluoroacetone and trioctylphosphine oxide in a micellar solution of triton X-100

The composition of the europium-thenoyltrifluoroacetone (TTA)-trioctylphosphine (TOPO) chelate in water in the presence of Triton X-100 was investigated. The stoichiometric composition was found to be Eu(TTA)(3)(TOPO)(2), but different compositions can occur depending on the relative concentrations of the ligands, The fluorescence properties of the ternary complex were examined and optimum experimental conditions were defined for the determination of europium over a wide range of concentrations. The fluorescence intensity was a linear function of europium concentration over six decades extending from 10(-11) to 10(-5) mol l(-1) with a detection limit of 6 x 10(-12) mol l(-1).