RESPONSE OF THE JALPAITE MEMBRANE COPPER(II) ION-SELECTIVE ELECTRODE IN MARINE WATERS

The response of the Orion 94-29 Cu-II ion-selective electrode (ISE) [e mploying a jalpaite membrane] in seawater has been related to levels o f free Cu-II yielding results for the Derwent River and San Diego Bay that are 2 to 3 orders of magnitude higher than those for the Pacific Ocean. Response data for the electrode in acidified seawater at pH 2 a re internally consistent with total Cu-II levels determined using diff erential pulse anodic stripping voltammetry (DPASV) and graphite furna ce atomic absorption spectrometry (GFAAS). It has been found that, eve n in acidified seawater. the organic ligands influence the response of the electrode, and this effect can be compensated successfully by eit her analyzing UV-photooxidized seawater and/or using a standard additi on technique, The assigned ISE results for total Cu-II in acidified se awater fall within +/- (0.1-0.5) pCu unit of values determined using G FAAS, Electrode drift in seawater can be minimized by using a polished electrode that has been conditioned in seawater for 24h. The improved response rate of a conditioned ISE minimizes electrode soaking times and sample contamination through membrane corrosion.