TY - JOUR
T1 - Determination of Aqueous FeIII/III Electron Self-Exchange Rates Using Enriched Stable Isotope Labels, Ion Chromatography, and Inductively Coupled Plasma Mass Spectrometry
AU - Kozerski, Gary E.
AU - Florentino, Michael A.
AU - Ketterer, Michael E.
PY - 1997
Y1 - 1997
N2 - A strategy is described for rapid on-line measurement of electron self-exchange rates between aqueous FeIII and FeII in aqueous solution using stable 57Fe-labeled reactants, cation chromatography, and inductively coupled plasma mass spectrometry. The self-exchange is monitored by mixing the reactants and performing timewise separations of FeII and FeIII ions. Separations are completed in 30-60 s using a weak phosphonic/carboxylic acid cation exchange guard column and 0.1-0.5 M aqueous HClO4 eluent. The resulting time series of 56Fe and 57Fe chromatograms display systematic changes in isotopic abundances from which the self-exchange rate constant, k11, is obtained. Two different schemes are used for mixing and sampling the reaction mixture; using a peristaltically pumped flow reactor, reaction half-lives on the order of 30 s can be monitored. A series of k11 results are obtained under a variety of temperature (2.0, 21.6, and 25.0 °C) and ionic strength conditions (0.10, 0.50, and 0.55 M aqueous HClO4) which are congruent with three previously published radiolabeling studies for this reaction.
AB - A strategy is described for rapid on-line measurement of electron self-exchange rates between aqueous FeIII and FeII in aqueous solution using stable 57Fe-labeled reactants, cation chromatography, and inductively coupled plasma mass spectrometry. The self-exchange is monitored by mixing the reactants and performing timewise separations of FeII and FeIII ions. Separations are completed in 30-60 s using a weak phosphonic/carboxylic acid cation exchange guard column and 0.1-0.5 M aqueous HClO4 eluent. The resulting time series of 56Fe and 57Fe chromatograms display systematic changes in isotopic abundances from which the self-exchange rate constant, k11, is obtained. Two different schemes are used for mixing and sampling the reaction mixture; using a peristaltically pumped flow reactor, reaction half-lives on the order of 30 s can be monitored. A series of k11 results are obtained under a variety of temperature (2.0, 21.6, and 25.0 °C) and ionic strength conditions (0.10, 0.50, and 0.55 M aqueous HClO4) which are congruent with three previously published radiolabeling studies for this reaction.
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U2 - 10.1021/ac960838y
DO - 10.1021/ac960838y
M3 - Article
AN - SCOPUS:1542708453
SN - 0003-2700
VL - 69
SP - 783
EP - 788
JO - Analytical Chemistry
JF - Analytical Chemistry
IS - 4
ER -