Intracellular magnesium ion-selective microelectrode based on a neutral carrier

Abstract
A magnesium ion selective microelectrode based on a synthetic neutral carrier is presented. The selectivity of Mg2+ over Na+, K+, H+, and Ca2+ is sufficient for assays of intracellular magnesium ion activities. The microelectrodes with an optimized membrane composition have a resistance of about 5 .times. 1010 .OMEGA. and a 90% response time of .ltoreq. 3 s for a tip diameter around 1 .mu.m. The lifetime of the microelectrode cell assembly is longer than 1 week and the emf drift after equilibration is .ltoreq. 0.3 mV/h.