Polymers in sensor applications

Porphyrins in analytical chemistry. A review.

The influence of ionic sites on the behavior of charged carrier-based ion-selective liquid membrane electrodes is described by theory and experiments for cation- and for anion-selective electrodes. The cation exchanger potassium tetrakis[3,5-bis-(trifluoromethyl)phenyl]borate proved to be a beneficial additive for nitrite-selective electrodes. On the other hand, the anion exchanger tridodecylmethylammonium chloride improved the potentiometric properties of cation-selective electrodes. By the incorporation of a defined amount of these sites, the selectivity was enhanced, the emf functions became theoretical, the electrode resistance was lowered, and the long-term stability improved. The optimal molar ratio of additive to ionophore was in the range of 0.3-0.6 for the ionophores studied

Ionic additives for ion-selective electrodes based on electrically charged carriers

We report a preliminary study on double carrier membrane systems that mimic, in principle, the function of ATPase, although chemical compounds involved are totally different. It shown that the transport of ions with a double carrier membrane system is facilitated more efficiently than the conventional symport system

Enhancement of uphill transport by a double carrier membrane system.

This article reviews recent advances in the field of potentiometric solvent polymeric membrane electrodes. These sensors have found widespread applications in a variety of fields, especially in the area of clinical diagnostics. Emphasis is given on the discussion of the theoretical and practical limits of ionophore-based ion-selective electrodes, with a special focus on electrode sensitivities, characterization of selectivities and dramatic improvements in detection limits. Advances in ionophore design and in the underlying model assumptions are also discussed. It is shown that a multitude of exciting new research possibilities have recently emerged in this well—established field.

Polymer Membrane Ion-Selective Electrodes–What are the Limits?

Lipophilic Co(III) and Mn(III) complexes of 5,10,15,20-tetrakis[4-(hexyloxycarbonyl)phenyl]porphyrin act as positively charged carriers for anions and induce anion selectivities in membranes clearly deviating from the sequence of classical anion exchangers. Different anion selectivities are observed for the Co(III) and Mn(III) porphyrins.

Anion Selectivity of Metalloporphyrins in Membranes

Aquocyanocobalt(III)-hepta(2-phenylethyl)-cobyrinate as a cationic carrier for nitrite-selective liquid-membrane electrodes

Selective transport of given substrates through artificial membranes can be achieved by incorporation of electrically neutral or charged carriers. Such mediated transport described for alkali and alkaline-earth metal cations is reported here for the first time for certain anions using cobyrinate-type ionophores, and it is also conceivable to be realized for nonionic substrates (e.g. glucose). The fundamental requirements for corresponding co-transport and counter-transport membrane systems are set forth in view of a design of novel substrate-selective sensors for analytical-chemical applications.

Bernhard Lindemann

Papers

Anion Selectivity of Metalloporphyrins in Membranes

Aquocyanocobalt(III)-hepta(2-phenylethyl)-cobyrinate as a cationic carrier for nitrite-selective liquid-membrane electrodes

Selective transport membranes and their applicability for novel sensors

Anion Selectivity of Metalloporphyrins in Membranes.