Cross sensitivity of potentiometric PD-sensors (sensors whose signal is Donnan potential) based on MF-4SC and Nafion cation-exchange membranes containing hydrated ZrO2 nanoparticles to amino acid (glycine, alanine, and leucine) ions in alkaline solutions has been investigated. By varying ZrO2 concentrations, it is possible to select pairs of PD-sensors that have a sufficiently high sensitivity to the amino acid anions and K+ cations in Gly + KOH, beta-Ala + KOH, and Leu + KOH solutions, as well as the lowest correlation between responses of sensors. The pairs of PD-sensors were used for simultaneous determination of amino acid anions and K+ cations in alkaline solutions.