(211a) Novel in Situ Methods for Floc Size Determination in Cell Culture Seperations

Recently flocculation has emerged as a viable option for the improvement of cell culture separations. The controlled flocculation of cells and cell debris can increase filtration and centrifugation speed, enhance throughput and improve clarification performance. Flocculation is particularly important for high density cell cultures where large amounts of biomass, especially in the sub-micron range, can prove challenging to effectively separate.

The particle size of flocculated cell debris is critical to consider when developing and implementing a flocculation step since it is often directly related to separation performance and will define requirements for the separation technology (pore size of depth filters for example). Offline particle size analysis tools have failed to gain broad acceptance for this task since flocs are inhernetly delicate and can break apart easily during the sampling, preparation and analysis phases of an offline analytical method. Also, the time delay between sampling and receipt of results can mean that expensive flocculants are added to a process for longer than needed

In this paper examples of how in situ measurement of floc size and count have being used to improve cell culture flocculation and separations will be presented. In situ monitoring using ParticleTrack technology will be shown to eliminate the most common errors associated with sampling and provide a more reliable method for the determination of flocculation onset, kinetics and endpoint. Examples relating flocculent dosage and type with floc size and stability will be presented and correlations between floc size and separation performance will be shown.