Poly(catechol) film modified glassy carbon electrode for ultratrace determination of cerium(III) by differential pulse anodic stripping voltammetry

Oxidative electropolymerization of resorcinol, catechol and pyrogallol at the glassy carbon electrode in different media such as 0.10 M NaOH, 0.10 M phosphate buffer (pH 7.00) or 0.10 M NaClO4 all gave water-insoluble films, adherent on the electrode surface. Amongst them electropolymerization of catechol at the GC electrode in 0.10 M NaOH provided a highly sensitive and selective film for Ce(III) and therefore, this poly(catechol) film modified glassy carbon electrode was exploited for the selective preconcentration of Ce(III) at open circuit, followed by its determination by differential pulse anodic stripping voltammetry both in batch and flow systems. Factors affecting the accumulation, stripping and removal steps were investigated and an optimized procedure was then developed. Under optimized conditions, for batch determination, the calibration plot was linear in the concentration ranges 2.00 x 10(-9) M-1.00 x 10(-8) M and 2.00 x 10(-8) M-1.00 x 10(-7) M Ce(III). A detection limit of 2.0 x 10(-10) M (0.027 ppb) (SN = 3) was found for a 10 min accumulation. For six successive determinations of Ce(III) at concentrations of 2.00 x 10(-7), 2.00 x 10(-8) and 2.00 x 10(-9) M, relative standard deviations were 3.36%, 1.76% and 4.08%, respectively. Similar results were obtained for continuous flow analysis. Interference from selected foreign ions and substances were examined. The developed method was applied to Ce(III) determination in human urine, both in batch and continuous flow systems.