Comparative studies on 1,3-Xylyl and 2-Bromo-1,3-xylyl crown ethers as ion-selective electrodes

Article abstract of DOI:10.1021/ac00020a016

1,3-Xylyl and 2-bromo-1,3-xylyl crown ethers have been tested as ion-selective electrodes in poly(vinyl chloride) (PVC) membranes. The pattern of selectivity appears to be essentially independent of ring size and probably reflects the ease with which substitution of water molecules from the inner hydration sphere of the ion can be effected. The ionophores have proved to be good K⁺ neutral carriers showing near-Nernstian responses to this ion, in the range 10^-1-10^-4 M. The fixed-interference method was used to determine relative selectivity coefficients for all the electrodes. The highest selectivity for potassium relative to sodium, lithium, calcium, and magnesium was obtained with 1,3-xylyl-15-crown-5 ether using NPOE plasticizer. The compounds tested exhibited a fast Nernstian response to changes in K⁺ concentration, which was stable to within <100 μV/h.