title: Hyphenated FT-IR-attenuated total reflection and electrochemical impedance spectroscopy technique to study the water uptake and potential stability of polymeric solid-contact ion-selective electrodes.
abstract: A new hyphenated method utilizing FT-IR-attenuated total reflection (ATR) and electrochemical impedance spectroscopy (EIS) is presented to correlate the water uptake with concomitant potential and impedance changes of polymeric coated-wire electrodes (CWEs) and solid-contact ion-selective electrodes (SCISEs). The Ca(2+)-selective silicone rubber (RTV 3140) based SCISEs with poly(3-octylthiophene) (POT) as the solid-contact (SC) showed good correlation between a very low water content at the Pt-coated ZnSe substrate/SC interface and a superior potential stability. This is due to the hydrophobicity of both RTV 3140 and POT and the approximately 2 orders of magnitude lower water diffusion coefficients in POT compared to RTV 3140. Practically no potential drift could be observed during 24 h when unconditioned CaSCISEs were contacted with 10(-3) M CaCl(2), in contrast to the Ca(2+)-selective CWEs with considerably higher water uptake and potential drift. The CaSCISEs had a fast Nernstian response with a detection limit of 8 × 10(-9) M Ca(2+) and a good reproducibility and stability of the standard potential, which indicates that the CaSCISEs does not require any conditioning prior to use.
authors.affiliation: Laboratory of Analytical Chemistry, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Åbo, Finland. Tom.Lindfors@abo.fi
authors.forename: Tom
authors.initials: T
authors.lastname: Lindfors
authors.forename: Lajos
authors.initials: L
authors.lastname: Höfler
authors.forename: Gyula
authors.initials: G
authors.lastname: Jágerszki
authors.forename: Róbert E
authors.initials: RE
authors.lastname: Gyurcsányi