Redox artificial buffers

Absorbance of the partly oxidized TF+-citrate solution is measured at 527 nm on a U 7V1S spectrophotometer. Released oxygen on a whole-plant basis is determined by extrapolation of the measured absorbance to a standard calibration curve. These hydroponic studies using artificial redox buffer may be useful in screening related response of wetland plants to reduced soil conditions. However, the conditions do not truly mimic the conditions in wetland soils. Oxidation of other reductants such as DOC, ferrous iron, and ammonium can also be used to estimate oxygen transport capacity of wetland plants (Reddy et al., 1990 Burgoon and Reddy, 1996). 

Most hydroponic studies of the response of wetland plants to anaerobic root environments have been based on the purging of nitrogen to remove oxygen from solution. Such treatments lead to a redox potential of 330-400 mV (DeLaune et al., 1990). This value is much higher than redox values found in flooded soils that may reach as low as -250 mV. Artificial redox buffer (titanium citrate) used to... 

Recently the oxidation of Cysteine in acidic medium (Robinson buffer) was reported at GO-cobalt phthalocyanine (GO-Co-1) hybrid immobilized at glassy carbon electrode (GCE) [181]. The electrochemical characterization of the obtained hybrid materials shows ill-defined redox couples attributed to the electroactivity of the cobalt centers. In presence of cysteine under acidic conditions (pH 3), an irreversible catalytic anodic peak was observed at 0.52 V versus Ag/AgCl, while no catalytic activity was observed in alkaline media (pH > 8). The study of electrode material performances was done by chronoamperometric experiments using several cysteine solutions, leading to a linear current variation in the concentration range of 0.03-200 mM with a detection limit of 5.0 nM. The stability of sensor was assessed, as well as its selectivity toward several interfering species including uric acid, ascorbic acid, GSH and nitrate in artificial solution. Finally, the hybrid electrode was also applied to the detection of cysteine in urine samples of healthy... 

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