RESPONSES OF H+ SELECTIVE SOLVENT POLYMERIC MEMBRANE ELECTRODES FABRICATED FROM MODIFIED PVC MEMBRANES

Potentiometric responses of a novel class of pH sensitive ionophores, namely several phenoxazine derivatives, were tested in different modif ied PVC matrices. The ionophores were compounded into liquid membranes as usual or were covalently coupled to the polymeric matrix. The gene ral analytical performance of the membranes and other membrane charact eristics (i.e., resistance and response time, as measures of membrane decomposition or structural changes) were followed in time. The transi ent responses of membranes with mobile ionophores in high molecular we ight (HMW) and carboxylated PVC (PVC-COOH) were compared to those with immobilized ionophores. The response time of membranes with immobiliz ed ionophores was found to be between those with mobile ionophores in HMW (fast response) and PVC-COOH (sluggish response). Accordingly, the rate of response was correlated primarily to the -COOH content of the membranes.