Oxygen, polarographic determination

Kreuzer, F., Kimmich, H. P., Brezina, M. Polarographic Determination of Oxygen in Biological Materials in Medical and Biological Applications of Electrochemical Devices (ed.) Koryta, J. Chapt. 6, New York, Wiley 1980... 

Karchmer, J.H. Polarographic Determination of Dissolved Oxygen. Study... 

Polarographic Determination of Oxygen. Anomalous Current Encountered... 

Enzymatic anti-interference layers containing oxidases can also be used to eliminate oxygen or prevent its diffusion into the electrode-near space. This enables the polarographic determination of organic com-... 

The enzyme catalyzes the incorporation of one atom of oxygen into L-lysine, and 8-aminonorvaleramide is formed concomitantly with the evolution of carbon dioxide. Enzyme activity was estimated by the polarographic determination of oxygen consumption. The concentration curve of L-lysine was sigmoidal, and 0.18 mM L-lysine was required for the half maximal velocity of the enzyme. 

Linhart, K., Polarographic determination of surface active materials in water and wastewater, and the determination of their degradibility (in German), Tenside, 1972, 9, 241-259. Bednarkiewicz, E., Z. Kublik, Surfactants by suppression of the polarographic maximum of the first kind, J. Electroanal. Chem. Interfacial Electrochem., 1987,218,93-106. Bednarkiewicz, E., Surfactants in fresh waters based on suppression of polarographic oxygen maximum. Electroanalysis (N.Y.), 1991, i, 839-845. 

Electrochemical analytical techniques are a class of titration methods which in turn can be subdivided into potentiometric titrations using ion-selective electrodes and polarographic methods. Polarographic methods are based on the suppression of the overpotential associated with oxygen or other species in the polarographic cell caused by surfactants or on the effect of surfactants on the capacitance of the electrode. One example of this latter case is the method based on the interference of anionic surfactants with cationic surfactants, or vice versa, on the capacitance of a mercury drop electrode. This interference can be used in the one-phase titration of sulfates without indicator to determine the endpoint... 

BASIC PROTOCOL 1 POLAROGRAPHIC MEASUREMENT OF OXYGEN UPTAKE Oxygen electrode equipment is used to determine oxygen uptake as a function of time. After preparing the enzyme (see Support Protocol) and calibrating the instrument, substrate and enzyme are added sequentially to a buffered solution, and the rate of oxygen uptake is monitored by a recorder. 

The detection of products derived from the N-oxygenation of C=N functionalities presents many problems, which illustrate difficulties that are associated with the isolation, identification and quantification of small amounts of water-soluble metabolites. Spectrophotometric methods19 as well as differential pulse polarographic techniques20 previously used to determine oximes, nitrones and N-oxides frequently lack sensitivity and/or specificity. Improved analytical methods for the quantification of these N-oxy compounds include chromatographic techniques taking into account the chemical peculiarities of the individual N-oxygenated C=N functionalities. These procedures usually require the chemical synthesis of authentic material for comparison with data obtained with the isolated metabolites, and also for the construction of calibration curves. 

In continuous reactors, for perfect mixing in each phase a measurement of the difference in concentration between outlet and inlet permits determination of kLaL. In practice, this method can be used for a reacting system when the liquid-phase concentration is maintained at a low value. Mukhopadhyay and Ghose (1976) employed this technique in large fermenters, where they measured gas-phase concentrations of oxygen at the inlet and outlet and the liquid-phase concentration in the fermenter using polarographic electrodes. 

Thermodynamic and kinetic measurements of the O2 binding process for the heme proteins are essential to discuss their physiological and chemical properties. Representative parameters are depicted in Table 1. The oxygen equilibrium can be directly determined by a polarographic-spectrophotometic method with an O2 electrode. The P50 value, the O2 pressure when half of the heme protein s 02-binding sites are occupied, is quite often used for the... 

All applications of the polarographic p02 electrode cannot be described here. Several examples which were reported may serve as an information source about a useful method for the determination of oxygen in biological samples. 

Substituted diarsines (Rj AS-ASR2) can be determined polarographically , the E j2 of the anodic wave being independent of the nature of the substituent. The analysis must be carried out in the absence of oxygen, which oxidizes the As—As bond. Concentrations of diarsines down to about 10 M can be determined by this procedure. 

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