Response time of ion-selective electrodes -: Current usage versus IUPAC recommendations

The current usage in evaluating the response speed of ion-selective electrodes is critically surveyed. Examination of the articles introducing new ISEs published in eight leading analytical and electroanalytical chemistry journals in the period 2000-2001 and of sparse articles appeared afterwards shows that the current IUPAC definition of response time, based on the differential quotient DeltaE/Deltat, is only used by a minority of authors. In its place, former IUPAC definitions, to be presently considered obsolete, or different expressions of the response speed are commonly preferred. In most instances, the reported data do not describe adequately the electrode behaviour. Stricter adherence to the most recent IUPAC recommendation, which is more rational and nearly related with the practical reading time, is to be stimulated. Wider use of faithful emf versus time plots also deserves to be encouraged. (C) 2004 Elsevier B.V. All rights reserved.