title: Chronopotentiometric carbonate detection with all-solid-state ionophore-based electrodes.
abstract: We present here for the first time an all-solid-state chronopotentiometric ion sensing system based on selective ionophores, specifically for the carbonate anion. A chronopotentiometric readout is attractive because it may allow one to obtain complementary information on the sample speciation compared to zero-current potentiometry and detect the sum of labile carbonate species instead of only ion activity. Ferrocene covalently attached to the PVC polymeric chain acts as an ion-to-electron transducer and provides the driving force to initiate the sensing process at the membrane-sample interface. The incorporation of a selective ionophore for carbonate allows one to determine this anion in a background electrolyte. Various inner electrolyte and all-solid-state-membrane configurations are explored, and localized carbonate depletion is only observed for systems that do not contain ion-exchanger additives. The square root of the transition times extracted from the inflection point of the chronopotentiograms as a function of carbonate specie concentration follows a linear relationship. The observed linear range is 0.03-0.35 mM in a pH range of 9.50-10.05. By applying the Sand equation, the diffusion coefficient of carbonate is calculated as (9.03 ± 0.91) 10(-6) cm(2) s(-1), which corresponds to the established value. The reproducibility of assessed carbonate is better than 1%. Additionally, carbonate is monitored during titrimetric analysis as a precursor to an in situ environmental determination. Based on these results, Fc-PVC membranes doped with ionophores may form the basis of a new family of passive/active all-solid-state ion selective electrodes interrogated by a current pulse.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Geneva , Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland.
authors.forename: Zdeňka
authors.initials: Z
authors.lastname: Jarolímová
authors.forename: Gastón A
authors.initials: GA
authors.lastname: Crespo
authors.forename: Xiaojiang
authors.initials: X
authors.lastname: Xie
authors.forename: Majid
authors.initials: M
authors.lastname: Ghahraman Afshar
authors.forename: Marcin
authors.initials: M
authors.lastname: Pawlak
authors.forename: Eric
authors.initials: E
authors.lastname: Bakker