Sample allowed redox potentials

The association of sulfur and iron into simple to more complex molecular assemblies allows a great flexibility of electron transfer relays and catalysis in metalloproteins. Indeed, the array of different structures, the interactions with amino-acid residues and solvent and their effect on redox potential and spectroscopic signatures is both inspiring for chemists and electrochemists, and of paramount importance for the study of these centers in native conditions. Most of the simpler natural clusters have been synthesized and studied in the laboratory. Particularly, the multiple redox and spin states can be studied on pure synthetic samples with electrochemical and spectroscopic techniques such as EPR or Fe Mossbauer spectroscopy. More complex assembhes still resist structural... 

Electrochemical detection is very sensitive for the compounds that can be oxidized or reduced at low-voltage potentials. Therefore, it could also be applied in the HPLC analysis of phenolic acids that are present in natural samples at very low concentrations. With the recent advances in electrochemical detection, multi-electrode array detection is becoming a powerful tool for detecting phenolic acids and flavonoids in a wide range of samples. The multi-channel coulometric detection system may serve as a highly sensitive way for the overall characterization of antioxidants the coulometric efficiency of each element of the array allows a complete voltametiic resolution of analytes as a function of their reaction (redox) potential. Some peaks may be resolved by the detector, even if they are unresolved when they leave the HPLC column. ... 

The principle of dual electrodes allowing both amperometric and potentiometric substrate determination has been described by Ianniello et al. (1982a). A reversible redox mediator, such as ferrocyanide, is added to the sample and either the diffusion current at constant potential or the redox potential at zero current is evaluated. 

Electron transfer was observed in samples containing DBMIB, as shown by the loss of triplet and formation of a g 2 radical. This may be due to the DBMIB having a higher redox potential than DPQ, allowing the reduction of quinone to occur more easily or perhaps that DBMIB has a higher affinity for the binding site. 

Finneran and Lovley [23] and Schmidt et al. [24] have discussed the thermodynamics of the MTBE and TBA degradation process in the presence of different terminal electron acceptors. Schmidt et al. [24] calculated the free energy AG° yield from MTBE or TBA under different redox conditions from oxic to methanogenic, where this value ranged from -3172 to -88.6 kj mol or from -2499 to -32.1 kJ mol respectively. This showed that although less favorable, anaerobic conditions could allow the biodegradation of MTBE and TBA. Bradley et al. [25] tested the mineralization potential of [ C]-MTBE in the presence of all the predominant electron acceptors with lake or stream sediments sampled at three different sites in the United States. Minerahzation was observed in all cases but to different extents. 

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