A Photo-Cured Coated Wire Potassium Ion-Selective Electrode for Use in Flow Injection Potentiometry

A potassium ion selective electrode (ISE) is reported based on the epoxyacrylate polymer prepared from o-nitrophenyl octyl ether as the plasticizer and 2,2′-bis [3,4-(15-crown-5-)-2-nitrophenylcarbamoxymethyl]tetradecane (BME-44) as the ionophore. Several different electrodes were studied by photo-curing different membranes onto a silver wire (0.8mm i.d.), and the response characteristics were evaluated. The membranes prepared exhibited strong adhesion to the metal substrate and showed improved mechanical strength compared to poly(vinyl chloride)-based membranes. The sensor exhibited Nernstian response over a log-linear range of between 0.01 mM and 100mM, and was selective against the common interfering ions. Fast response reaching 90% of steady-state value in 5 s makes this sensor applicable for flow injection potentiometry measurements. The potassium ISE allows for accurate determinations of potassium in various water samples by flow injection potentiometry.