Response of a copper(II) and iron(III) ion-selective electrode bielectrode array in saline media

A bielectrode array comprising a jalpaite membrane (i.e., Ag1.5Cu0.5S) copper(II) ion-selective electrode (ISE) and chalcogenide glass membrane (i.e., Fe2.5(Se60Ge28Sb12)97.5) iron(III) ISE has been assembled by individually wiring each solid-state sensor into a single electrode body. Furthermore, a dual metal ion buffer calibration standard incorporating copper(II) and iron(III) coordinating ligands to regulate the levels of free copper(II) and iron(III) in the buffer has been developed to enable simultaneous calibration of the bielectrode ISE array. In this work, the bielectrode ISE array has been employed in the continuous flow analysis (CFA) of free copper(II) and iron(III) in seawater media. It is shown that the individual electrodes displayed Nernstian response in the metal ion buffer calibration standard over a wide dynamic range (viz., 10−15 to 10−5 M aCu2+ and 10−21 to 10−11 M aFe3+), and the results of repetitive CFA analyses of free copper(II) and iron(III) in seawater are commensurate with the typical values found in coastal seawater samples. Clearly, the bielectrode ISE array may be used in the simultaneous analysis of free copper(II) and iron(III) in seawater without fear of cross-interference between the solid-state sensors.