Nitrate-selective chemically modified field effect transistors for flow-cell applications Original Research Article

The paper presents studies devoted to the optimization of nitrate-selective membrane composition of CHEMFETs designed for flow-cell system. The influence of the structure of the quaternary ammonium salts and its concentration on the PVC membrane selectivity was investigated. The highest nitrate selectivity and almost theoretical response were obtained for CHEMFETs based on o-NPOE/PVC membranes containing 1% of symmetrical tetradodecylammonium nitrate. Slightly lower nitrate selectivity of CHEMFETs was obtained using silicon rubber polymer (Siloprene) membrane. However, improved adhesion properties to the gate surface ensured their better durability (at least 3 months) comparing to sensors based on plasticized PVC membranes. Experimental data measured in this work were fitted to Nikolski–Eisenman equation, which simplify the estimation of the calibration curves and the determination of the potentiometric selectivity coefficients.