Besides for electrochemical analysis, polarographic electrochemical analysis, polarographic elecrtrodes can be used for the determination of hydrodynamic parameters in aqueous media. For this latter application, a three-segment microelectrode has been developed with which vectorial hydrodynamic parameters (liquid velocity and turbulence intensity) can be determined via elecrtrodiffusion. With oxygen instead of the normally used ferri-/ferrocyanide system, the microelectrrode can be employed for hydrodynamic measurements in aerated aqueous solutions independent on coalescence behavior. Experiments show that in contrast to Laser-Dopler Anemometry and Hotfilm Anemometry the electrodiffusion electrode can also be used in aerated solid suspensions. Moreover, using the probe with oxygen as the depolarizer, it is possible to measure hydrodynamic parameters and dissolved oxygen concentration at the same time. As an example, the simultaneous determination of hydrodynamics and oxygen in aerobic batch fermentation (Erwinia herbicola) is presented.
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