Direct sensing of total acidity by chronopotentiometric flash titrations at polymer membrane ion-selective electrodes.

ABSTRACT: Polymer membrane ion-selective electrodes containing lipophilic ionophores are traditionally interrogated by zero current potentiometry, which, ideally, gives information on the sample activity of ionic species. It is shown here that a discrete cathodic current pulse across an H (+)-selective polymeric membrane doped with the ionophore ETH 5294 may be used for the chronopotentiometric detection of pH in well-buffered samples. However, a reduction in the buffer capacity leads to large deviations from the expected Nernstian response slope. This is explained by the local depletion of hydrogen ions at the sample-membrane interface as a result of the galvanostatically imposed ion flux in direction of the membrane. This depletion is found to be a function of the total acidity of the sample and c

SUBMITTER: Gemene KL 

PROVIDER: S-EPMC2574779 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature