The water uptake of plasticized poly(vinyl chloride) solid-contact calcium-selective electrodes

Tom Lindfors, Fredrik Sundfors, Lajos Höfler, Róbert E. Gyurcsányi

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28 Citations (Scopus)


A hyphenated method based on FTIR-ATR and electrochemical impedance spectroscopy has been applied to simultaneously measure the water uptake, changes in the bulk resistance and potential of plasticized poly(vinyl chloride) (PVC) based Ca2+-selective coated-wire (CaCWE) and solid-contact electrodes (CaSCISEs). Most of the water uptake of the ion-selective membranes (ISMs) used in both electrode types took place within the first 9h in 10-3M CaCl2 showing good correlation with the stabilization of the individual electrode potentials. The bulk resistance of the ISMs of the CaCWEs and the CaSCISEs with poly(3-octylthiophene) (POT) as the solid-contact (SC) increased most during the first 18h in 10-3M CaCl2. The increase in the resistance was found to be related to the exchange of K+ for Ca2+ in the ISM and the formation of the Ca2+-ionophore (ETH 5234) complex having a lower diffusivity than the free K+ ions. In contrary to previously published results on silicone rubber based SCISEs and poly(methyl methacrylate):poly(n-decyl methacrylate) membranes containing POT, the plasticized PVC-based CaSCISEs with POT as the SC had a higher water uptake than the CaCWEs. The CaSCISEs had a detection limit of 2×10-8M Ca2+ and a good potential reproducibility of 148.9±1.0mV in 10-4M CaCl2.

Original languageEnglish
Pages (from-to)2156-2163
Number of pages8
Issue number9
Publication statusPublished - Sep 1 2011



  • Electrochemical impedance spectroscopy
  • FTIR-ATR spectroscopy
  • Plasticized poly(vinyl chloride)
  • Poly(3-octylthiophene)
  • Potential stability
  • Solid-contact ion-selective electrode
  • Water uptake

ASJC Scopus subject areas

  • Analytical Chemistry
  • Electrochemistry

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