Behavior and calibration of the copper(II) ion-selective electrode in high chloride media and marine waters

Abstract

The response of the solid-state Cu(II) ion-selective electrode in high chloride media was investigated and found to be Nernstian under normal laboratory and field measurement conditions. The previously reported «non-Nernstian» behavior has been identified as a combination of electrode fouling, due to specific storage and measurement conditions, and the action of stoichiometric levels of a Lewis base on the standard addition method of electrode calibration. Electrode calibration by external Cu(II) activity buffers in artificial sea-water is described. The copper activity of the buffers is calculated from an ion-interaction model, and the electrode response in these buffers is shown to be consistent with that in chloride solutions over 10 orders of magnitude copper concentration and from pH 8 to 2