Magnesium Selective Microelectrode Based on a Neutral Carrier with Mixed-Solvent

Abstract

An intracellular ion-selective microelectrode based on the neutral carrier ETH5214 with chlorinated paraffin (60% Cl) and o-nitrophenylocytylether (o-NPOE) as solvents is presented. Compared with the sensor based on the same ionophore with solvent o-NPOE, the potentiometric selectivity factor for Mg2+ with respect to K+ has been improved by 0.9 order of magnitude. The microelectrode shows a near-Nernstian response in pure MgCl2 solutions and in the MgCl2 solutions at a typical intracellular ion background, with detection limits of 4 x 10(-7) mol.dm-3 and 2 x 10(-5) mol.dm-3, respectively. The H+ does not interfere with the emf response of the electrode in pH 3.5-9.5. The lifetime of the microelectrode cell assembly is longer than 5 days, and the response time (t95) less-than-or-equal-to 3 s.