Sulfonated poly(ether ether ketone), an ion conducting polymer, as alternative polymeric membrane for the construction of anion-selective electrodes

A novel arrangement for polymeric membranes used in anion-selective electrodes is presented. Sulfonated poly(ether ether ketone) (SPEEK), an ion conducting polymer has been used as a polymeric matrix to build an anion-selective electrode (ISE). A NO3−-ISE has been chosen as a model electrode to study the efficiency of the polymeric membrane. The effect of membrane composition and polymer compatibility with the electro-active components was investigated. The polymer matrix showed good mechanical properties and can be solvent cast in complete analogy to traditional ISE membranes. SPEEK matrix was studied in order to optimize both the potentiometric response and the selectivity of the electrode. The electrode exhibited a linear response with a slope of −51 mV per decade within the concentration range from 8.0 × 10−5 to 2.5 × 10−2 M nitrate ion. The detection limit was found to be 5.0 × 10−5 M, and electrodes could be used over a wide pH range of 4–8. Finally, the sensor showed improved selectivity in comparison to some of the previously reported nitrate-selective electrodes.