This work describes the fabrication and usability of organic polymeric layers as gate insulators of field effect transistors (reference field effect transistors, REFET) that are dedicated to the determination of pH-reference potentials in electrolytic solutions. Based on the site binding model hydrophobe CF-polymers were investigated. Various techniques are able to generate polymeric layers that are characterized by low selective hydrogen ion sensitivity. Additional results indicate the necessity of reexamination the site binding model´s usability for polymers with low amount of dissociating sites. This work suggests a model assuming ion adsorption onto polymeric surfaces. This model describes results from CV-measurements as well as measurements on REFETs in a qualitative and quantitative way