Flow-through tubular iodide and bromide selective electrodes based on epoxy resin heterogeneous membranes

Tubular all-solid-state iodide and bromide selective electrodes with channels drilled through the crystalline heterogeneous membranes have been prepared for use in flow-injection analysis (FIA). The membranes, made with AgX/Ag(2)S powdered mixtures (X = I, Br) dispersed in a non-conductive epoxy resin, were assembled inside a hollow cylindrical support of conductive epoxy resin. The response characteristics of these detectors, in a low-dispersion FIA system, have been evaluated. Both show a Nernstian response over the range between 5 x 10(-5) and O.1M X(-), good reproducibility and fast response, which allows a sampling rate of 60/hr. Operational pH ranges from 2.5 to 11 and from 3 to 10 were obtained for the iodide and bromide electrodes respectively. Iodide must be absent in determinations with the bromide electrode.