title: New Signal Readout Principle for Solid-Contact Ion-Selective Electrodes.
abstract: A novel approach to signal transduction concerning solid-contact ion-selective electrodes (SC-ISE) with a conducting polymer (CP) as the solid contact is investigated. The method presented here is based on constant potential coulometry, where the potential of the SC-ISE vs the reference electrode is kept constant using a potentiostat. The change in the potential at the interface between the ion-selective membrane (ISM) and the sample solution, due to the change in the activity of the primary ion, is compensated with a corresponding but opposite change in the potential of the CP solid contact. This enforced change in the potential of the solid contact results in a transient reducing/oxidizing current flow through the SC-ISE. By measuring and integrating the current needed to transfer the CP to a new state of equilibrium, the total cumulated charge that is linearly proportional to the change of the logarithm of the primary ion activity is obtained. In this work, different thicknesses of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) were used as solid contact. Also, coated wire electrodes (CWEs) were included in the study to show the general validity of the new approach. The ISM employed was selective for K(+) ions, and the selectivity of the membrane under implementation of the presented transduction mechanism was confirmed by measurements performed with a constant background concentration of Na(+) ions. A unique feature of this signal readout principle is that it allows amplification of the analytical signal by increasing the capacitance (film thickness) of the solid contact of the SC-ISE.
authors.affiliation: Laboratory of Analytical Chemistry, Johan Gadolin Process Chemistry Centre, Åbo Akademi University , Biskopsgatan 8, FI-20500 Åbo, Finland.|Laboratory of Materials Chemistry and Chemical Analysis, University of Turku , Vatselankatu 2, 20500 Turku, Finland.
authors.forename: Ulriika
authors.initials: U
authors.lastname: Vanamo
authors.affiliation: Laboratory of Analytical Chemistry, Johan Gadolin Process Chemistry Centre, Åbo Akademi University , Biskopsgatan 8, FI-20500 Åbo, Finland.|Graduate School in Chemical Engineering (GSCE), Åbo Akademi University , Tavastgatan 13, FI-20500 Åbo, Finland.
authors.forename: Elisa
authors.initials: E
authors.lastname: Hupa
authors.affiliation: Laboratory of Analytical Chemistry, Johan Gadolin Process Chemistry Centre, Åbo Akademi University , Biskopsgatan 8, FI-20500 Åbo, Finland.
authors.forename: Ville
authors.initials: V
authors.lastname: Yrjänä
authors.affiliation: Laboratory of Analytical Chemistry, Johan Gadolin Process Chemistry Centre, Åbo Akademi University , Biskopsgatan 8, FI-20500 Åbo, Finland.
authors.forename: Johan
authors.initials: J
authors.lastname: Bobacka
mesh_terms: D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D004566:Electrodes; D017736:Ion-Selective Electrodes; D007477:Ions / Q000032:analysis; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D011188:Potassium / Q000032:analysis*; D012964:Sodium / Q000032:analysis
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D007477:Ions; D011108:Polymers; D011137:Polystyrenes; C121383:poly(3,4-ethylene dioxythiophene); C003321:polystyrene sulfonic acid; D012964:Sodium; D011188:Potassium