Potentiometric investigations using pressed zeolite discs are reported. Pot
ential measurements have been performed in non-aqueous solutions-this is th
e first report, to our knowledge, of potentiometric detection of ions in no
n-aqueous media with zeolite materials. Nernstian behaviour is also display
ed in aqueous solutions for ions that are only able to penetrate a fraction
of the internal volume of the zeolite employed.