Investigation of poly(3,4-ethylenedioxythiophene) deposition method influence on properties of ion-selective electrodes based on bis(benzo-15-crown-5) derivatives

Glassy carbon electrodes modified by conductive polymers and membrane with derivatives of bis(benzo-15-crown-5) were tested as solid contact ion selective electrodes for K+ ions concentration determination. PEDOT with PSS, Cl− and ClO4− counter ions was electrochemically deposited onto glassy carbon substrates using four different electrochemical approaches (potentiostatic, galvanostatic, potentiodynamic and potentiostatic pulses). Scanning electron microscopy was applied to investigate influence of electrodeposition method on morphology of polymer films and drop-casted pseudo liquid membrane with an ionophore. The presence of the polymer film and method of deposition affect morphology of tested electrodes and sensing properties as well. The best sensing properties were obtained for the electrodes with biscrown I as ionophore with polymer which have a developed surface prepared via potentiostatic pulses (logKK/Na = −5.6 using separate solution method (SSM 1M)). Galvanostatic method of electrodeposition which resulted in relatively smooth layer of the PEDOT exhibited the poorest sensing properties for sensor with biscrown I as ionophore (logKK/Na = −4.3 for SSM 1M). All prepared sensors exhibited very favorable values of selectivity coefficients KK/Na (log KK/Na = −5.6 - -4.0). Detection limit equals to 10−7 M was achieved. The influence of pH for sensing properties were investigated for the selected electrodes.