A photo‐cured coated wire potassium ion‐selective electrode for use in flow injection potentiometry

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Abstract
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 (0.8 mm 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 100 mM, 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.