Membrane based on decyl-18-crown-6 for a potassium selective sensor

Four kinds of 18-crown-6 derivatives were studied as ionophores in plasticized poly(vinyl chloride) (PVC) in order to obtain potassium selective membrane. The properties of the sensor were studied in detail. For the optimization of the selectivity toward K+ over Na+ the influence of the following factors was studied: nature and concentration of the ionophore; nature and concentration of the plasticizer and lipophilic salt addition. The potassium ion-selective membrane electrode was designed. The electrode has a fast and Nernstian response in the 1 x 10(-1)-2 x 10(-5) mol l(-1) K+, after six months of continuous measurements. The change of pH in the range 2-10.5 does not affect the response of the electrode. The internal resistance of the electrode was measured. The electrode shows a good stability and can be used in the potentiometric determination.