Lipophilic and immobilized anionic additives in solvent polymeric membranes of cation-selective chemical sensors

Selectivity-modifying influence of anionic sites in neutral-carrier-based membrane electrodes

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?

The well-known selective receptor properties and ease of structural modification makes calixarene derivatives attractive materials for use in chemical sensors. This review looks at the history of sensor-related calixarene research prior to 1994 and identifies current trends in sensor research which are influencing the types of derivatives being synthesised and methods of evaluation, such as the increasing popularity of optical modes of transducing host-guest interaction. Future possibilities are briefly discussed and the need for more fundamental studies highlighted.

Calixarene-based sensing agents

Coordination chemistry of calix[4]arene derivatives with lower rim functionalisation and their applications

Polymeric membrane sodium-selective electrodes based on lipophilic calix[4]arene derivatives

Previous Li/sup +/-selective polymeric membrane electrodes based on 14-crown-4 derivative 1 have been improved in the Li/sup +/ selectivities against Na/sup +/ and K/sup +/ by using 2 and 3 as the neutral carrier. Examination of the membrane solvents for the electrodes allowed further enhancement in the Li/sup +/ selectivities. An excellent k/sub LiNa//sup Pot/ value of 1.3 x 10/sup -3/ was attained with the poly(vinyl chloride) membrane containing 2 as the neutral carrier and o-nitrophenyl phenyl ether/tris(2-ethylhexyl) phosphate (98/2) as the solvent. Serum Li/sup +/ assay was successfully achieved with an electrode containing a combination of the optimized membrane based on the crown ether and a dialysis membrane, which eliminated interference by proteins in the samples.

Tsutomu. Miura

Papers

Polymeric membrane sodium-selective electrodes based on lipophilic calix[4]arene derivatives

Lithium ion selective electrodes based on crown ethers for serum lithium assay.

Lithium ion selective electrodes based on 14-crown-4 derivatives bearing lipophilic substituents as ionophores.