All-solid-state miniaturised planar reference electrodes based on ionic liquids

The paper presents the design of all-solid-state miniaturised reference electrodes suitable for flow-through analysis. The sensors are based on Ag/AgCl planar microelectrodes covered with PVC membranes containing an ionic liquid (IL, 1-dodecyl-3-methylimidazolium chloride). The membrane with IL additive provides an internal solid electrolyte, maintaining constant chloride concentration in the layer and thus constant potential of the Ag/AgCl electrode in solution of different concentration of chloride and other interfering anions. The performance of the reference microelectrodes with different ionic liquid content in the membrane was determined. The electrodes exhibited good potential stability, reproducibility and long-term stability. The structures were applied as reference electrodes in flow-cell measurements with potassium-selective planar microelectrodes. Comparable calibration curves of K+-selective electrodes determined using the designed reference microelectrodes based on ionic liquid and a commercial Ag/AgCl reference electrode were obtained.