Design of ionophores for ion-selective microsensors.
Requirements for a reliable use of liquid membrane microelectrodes are discussed in terms of stability, response time, and lifetime on the basis of membrane technological considerations. The selectivity of H+, Li+, Na+, K+, Mg2+, Ca2+, and Cl- microelectrodes is critically evaluated using the Nikolskii-Eisenman formalism. Recent progress in the design of new ionophores is presented. A novel neutral carrier-based Ca2+-selective microelectrode with a detection limit of about 5 X 10(-10) M Ca2+ at a background of 125 mM K+ has been realized. An neutral carrier-based microelectrode for H+ with extended pH range of the sample solution is now available. Promising developments in the field of Li+-, Mg2+-, and Cl--selective ionophores are discussed.
Ammann
D
D
Oesch
U
U
Bührer
T
T
Simon
W
W
D000818:Animals; D004563:Electrochemistry / Q000295:instrumentation*; D007476:Ionophores; D007477:Ions / Q000032:analysis* / Q000502:physiology; D008839:Microelectrodes / Q000592:standards
D007476:Ionophores; D007477:Ions