Carrier antibiotics and model compounds as components of selective ionsensitive electrodes. Pure Appi

The ion selectivity exhibited by different types of membrane electrodes is rationalized by a theoretical treatment of the membrane potential. An equation, which is admirably suited for the interpolation of e.m.f.-values, is derived for the electrode response of membrane electrodes of the electrically neutral ligand type (antibiotics, model compounds) to mixed solutions of monovalent and divalent cations. In contrast to the classical Nicolsky equation it describes the contribution of interfering ions to the e.m.f. by an activity-independent selectivity term. Electrically neutral ligands selective for calcium ions to be used as com-ponents for liquid membrane electrodes were designed and prepared. The corresponding electrodes are in all respects superior to the calcium ion liquid membrane electrodes described so far. In the past decade, a great number of selective ion-sensitive electrodes have been designed and have found application in all branches of routine analy