Fluoride electrode with LaF3-membrane and simple disjoining solid-state internal contact

Fluoride-selective electrode with LaF3-membrane and stainless steel internal contact has been prepared. The electrode has been tested in F− concentration range 10−2–10−6 M and the results compared with those of commercial electrode and electrode with laboratory renewed internal electrolytic contact. The properties of simple disjoining solid-state contact have been investigated by means of electrochemical impedance spectroscopy (EIS). The impedance spectra show two time constants, which suggest that, at lower frequencies, proceed some Faradic reaction which probably stabilizes the potential between LaF3-membrane and stainless steel disk.