期刊
ANALYTICA CHIMICA ACTA
卷 518, 期 1-2, 页码 93-100出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.aca.2004.05.040
关键词
oxygen sensors; electrodes optrodes; optodes; dissolved oxygen; voltammetry
Accurately measuring dissolved oxygen concentrations in fresh and saltwater environments has long been an interdisciplinary priority., Many methodologies exist, including two very promising new ones, optical fluorescence quenching optrodes (or optodes) and solid-state voltammetric electrodes. In this study we compare the responsiveness of these two techniques to dynamic changes in dissolved oxygen concentrations, using, traditional methods of polarographic oxygen sensors and Winkler's chemical titrations to corroborate the measurements. Advantages. of the optrode system include simplicity of operation and high sensitivity when changes in oxygen concentrations are small ( < Delta10 muM O-2 min(-1)). Advantages of voltammetry include equally high sensitivity, independent of rate of change of oxygen concentration, and the capability of simultaneously measuring other chemical species. Both systems have the capability of producing high-resolution, continuous oxygen profiles by collecting and reporting real-time data. Kinetic estimates of the binding and dissociation constants for the ruthenium-oxygen complex in the optrode revealed a relatively long half-life of the Ru2+-O-2 complex for dissociation (t(1/2) of 43.2s to equilibrate from a 100 to 0% O-2 saturation change). In contrast, the Ru2+-O-2 association constant was 5.0 times faster (t(1/2) of 8.6 s to equilibrate from a 0 to 100% O-2 saturation change). Therefore, because of these differential kinetics, researchers should take care when using a ruthenium-based optrode to measure real-time dissolved oxygen concentrations undergoing temporal variability. (C) 2004 Published by Elsevier B.V.
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