Plasticizer-free all-solid-state potassium-selective electrode based on poly(3-octylthiophene) and valinomycin

All-solid-state potassium-selective electrodes with plasticizer-free membra nes were prepared by incorporation of valinomycin as the ionophore and pota ssium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic addi tive in a semiconducting conjugated polymer matrix of poly(3-octylthiophene ). The membrane components were dissolved in chloroform and deposited on gl assy carbon by solution casting resulting in all-solid-state potassium sens ors. The analytical performance of the potassium sensors were studied by po tentiometric measurements. Electrochemical impedance spectroscopy was used to obtain information about the charge transfer and double layer charging p rocesses in the electrodes. The results show that a plasticizer-free all-so lid-state potassium-selective electrode can he prepared and that the electr on transfer at the glassy carbon/membrane interface plays a significant rol e in the signal transduction. (C) 1999 Elsevier Science B.V. All rights res erved.