Abstract: The preconcentration and stripping processes of cathodic stripping voltammetric determination of Eu(Ⅲ) by using tri-n-octylphosphine oxide modified electrode in a ternary complex system are characterized in this report by infrared and X-ray photoelectron spectroscopies. It states that the preconcentration efficiency is enhanced greatly with the formation of the ternary complex, Eu(TTA)₃(TOPO)₂, during the preconcentration process of the modified electrode. During the complexing preconcentration process, not all the tri-n-octylphosphine oxides at the electrode surface have the complex activity. Only those sites with the complex activity and favorable steric arrangement circumstance take part in the preconcentration complex reaction. It is shown that the Eu in the ternary complex at the electrode surface is reduced during the cathodic stripping process.

Key words: Chemically modifided electrode, Electrode surface characterization, Infrared spectra, X-ray photoelectron spectroscopy