Solid-state ion-selective electrode arrays

Variable pressure scanning electron microscopy is demonstrated to be a powerful method for directly studying swelling processes occurring during conditioning of PVC-membrane ion-selective electrodes containing a salt-doped hydrogel layer between the PVC and the internal Ag/AgCl reference electrode. Using an in-house developed virtual instrument interface and a portable PC fitted with a PCMCIA data acquisition card, it is relatively easy to adapt arrays manufactured for blood-gas analysis for other applications which involve the determination of mixtures of inorganic ions. The simultaneous analysis of sodium and chloride over concentration ranges associated with the diagnosis of cystic fibrosis (CF) in sweat is demonstrated as an example.