NH4+-sensitive chemically modified field effect transistors based on siloxane membranes for flow-cell applications Original Research Article

The paper describes the design and application of electrochemical microsensors based on field effect transistors (CHEMFETs) for selective ammonium ion determination. The ammonium-sensitive sensors utilize silicon rubber polymer (Siloprene) and polysiloxane PSX 851 membranes containing nonactine as an ionophore. The performances of ammonium-sensitive CHEMFETs were determined in a flow-cell system. Designed microsensors exhibit good selectivity for ammonium ions over alkali metal cations (except potassium) and over alkaline-earth metal cations. They showed linear response in a wide range of pNH4+ with a slope of 46–52 mV decade−1 and response times not exceeding 120 s. Best results i.e. highest values of response slope and highest selectivity over alkali metal cations were obtained for ammonium-sensitive CHEMFETs based on PSX 851 polysiloxane membranes.