The effect of heat treatment at varying relative humidity and mechanical deformation on the properties of Nafion perfluorosulfonic cation-exchange membranes and Nafion-based hybrid materials containing hydrated zirconia nanoparticles has been studied. It has been shown that the treatment of the materials makes it possible to change their water uptake, ionic conductivity, and diffusion permeability over wide ranges. Variations in the water uptake and intrapore space volume of the membranes provided by their treatment and modification have led to a decrease in the sensitivity of DP-sensors (the analytical signal is the Donnan potential) to interfering hydroxonium cations in arginine and histidine solutions in 1.5-5 times. The material samples providing a high accuracy of determination of amino acid ions in a concentration range from 1.0 x 10(-4) to 1.0 x 10(-1) mol/L at pH < 7 have been selected.