A simple dynamic method for on-line and off-line determination of kLa during cultivation of animal cells

Summary A new, fast method is described to determine k_La either off-line, or on-line during animal-cell cultivation. Since it does not need the equilibrium concentration of oxygen in the liquid phase (C*), it is not required to await a new steady state. Furthermore, the results do not depend on the calibration value of the dissolved-oxygen probe. The method yielded accurate values for k_La, both for an oxygen-consuming and a non-consuming system.Nomenclature C _L Dissolved-oxygen concentration mol·m^-3] - C ^* C _L in equilibrium with the oxygen concentration in the gas phase mol·m^-3] - C _L, Equilibrium oxygen concentration at stationary conditions mol·m^-3] - k_La Volumetric oxygen transfer coefficient s^-1] - r Specific oxygen consumption of biomass mol·cell^-1·s^-1] - X Cell concentration cells·m^-3] - t Time s] - Noise of dissolved-oxygen probe mol·m^-3] - Absolute error of k_La-measurement s^-1]