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Development of Magnesium‐Ion‐Selective Microelectrodes Based on a New Neutral Carrier ETH T 5504
Author(s) -
Zhang Xueji,
Fakler Alphons,
Spichiger Ursula E.
Publication year - 1998
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/(sici)1521-4109(199811)10:17<1174::aid-elan1174>3.0.co;2-a
Subject(s) - microelectrode , magnesium , molality , chemistry , analytical chemistry (journal) , electrode , ion , inorganic chemistry , detection limit , chromatography , organic chemistry , aqueous solution
Two types of magnesium‐selective microelectrodes based on a new synthetic neutral carrier ETH T 5504 are presented. One type of microelectrode is applicable to the determination of intracellular free Mg 2+ molality without interference from alkaline or alkaline‐earth metal ions versus a typical intracellular ion background of 10 mmol/L NaCl, 100 mmol/L KCl, and 1 μM CaCl 2 . The response function showed a slope of 28.6 ± 0.4 mV (1 SD per decade), and a detection limit at 10 −5.1 ± 0.1 mol/L. A magnesium‐selective electrode with different composition of the membrane cocktail has been employed for assays of both intracellular and extracellular Mg 2+ ‐activities, with improved discrimination of Ca 2+ and other physiological cations compared to electrodes based on ETH 1117, ETH 5214 and ETH 7025, respectively. This is the first report where Mg 2+ ‐selective microelectrodes can be applied to extracellular Mg 2+ ‐measurements. The microelectrodes based on ETH T 5504 perfectly discriminate the physiological extracellular ion background. Electrodes with tip diameters of typically 1 μm have an average electrical resistance of 3.0 × 10 10 Ω, and a response time, t 90 % , of 3 s. The lifetime of the microelectrodes is longer than 1 week and the emf‐drift after 1day conditioning period is ≤0.3 mV/h. An example of measurements of the Mg 2+ ‐molality in low volumes of specimen is described in this article for blood serum of rats.