Description
The dialysis probe provides the perfect solution for sterile online sampling in connection with an online analyser (e.g. BioPAT® Trace and BioPAT® Multi Trace) in bioreactors used in industrial and laboratory facilities. The dialysis probe in its entirety is made of stainless steel and ensures a high level of sterility by the use of an extremely robust membrane. The dialysis probe is installed in the bioreactor and sterilized in situ.It is suitable for all types of cultivation and can be installed in the bioreactor as well as in the PG 13.5 and 19 mm top plate and in a 25 mm side port. Optimal results can only be achieved if the membrane is completely immersed. Therefore, a minimum immersion depth of 5 cm is required. The application options for the dialysis probe depend on the reactor dimensions and the process conditions. In general, the dialysis probe is recommended for use on smaller bioreactors, where any loss of volume during sampling is unacceptable. The use of the dialysis probe as a sampling system ensures analysis at constant volumes. This probe functions by time-dependent diffusion of sample across a 12 kDa permeable membrane. The transport buffer and vessel solution do not directly mix. If the dialysis probe is used to feed the sample from the bioreactor into an online analyser, then the analyte is transferred through a diffusion membrane into an internal pump-driven buffer stream and transported to the measuring cell.
However, during the BioPAT® Trace sampling cycle the transport buffer flow is paused and the concentration gradient drives small molecules from the bulk into the transport buffer. When flow is resumes after a set time period, this accumulated concentration is transported to the biosensor for analysis. This data is then correlated to the linear calibration to yield the bulk concentration. This sampling method uses the diffusion of small molecules across the permeable membrane without any loss of vessel volume.
