Cleaning Polyethersulfone Membranes After Ultrafiltration-Diafiltration in Monoclonal Antibody Production - Polyethersulfone membranes can be cleaned safely, effectively, and economically. - BioPharm

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Cleaning Polyethersulfone Membranes After Ultrafiltration-Diafiltration in Monoclonal Antibody Production
Polyethersulfone membranes can be cleaned safely, effectively, and economically.


BioPharm International
Volume 19, Issue 4

Normalized Water Permeability


Table 1. UF-DF cleaning and operation condition parameters
NWP is an established method for determining the cleanliness of a membrane cassette after cleaning. The method involves measuring the passage of clean water through the membrane under standard pressure and temperature conditions (Table 1). The rate of clean water flux through the membrane is measured as liters per meter squared per hour (LMH). Water flux divided by the transmembrane pressure (TMP) is the NWP (LMH/psi).






Table 2. Normalized water permeability of the membrane before and after ultrafiltration-diafiltration
As shown in Table 2, after the membrane was used in the UF-DF process, it was reduced to about 20 percent of the pre-process NWP. Previous experiments showed that cleaning the membrane with 0.5N NaOH was not sufficient to recover the initial water permeability of the membrane (data not shown). Therefore, the authors used a solution of 0.5N NaOH with 250 ppm hypochlorite solution in an attempt to recover the permeability of the membrane.




Figure 3 shows NWP levels of a membrane following results from 10 cycles of a UF-DF step in a monoclonal antibody process, with cleaning after each use with 250 ppm hypochlorite in 0.5M NaOH at room temperature. The results in Table 2 show that after the 10 runs, the NWP was recovered to an average of 91 percent of the initial, pre-use value.


Figure 3. Results of normalized water permeability after cleaning the membrane post ultrafiltration-diafiltration






Process Flux (measure of process reproducibility)


Figure 4. Results of process flux for ten cycles
The goal of a cleaning cycle is to ensure consistent process performance. Process flux is another measure of how well the membrane has been cleaned. The UF-DF process throughout the 10 cycles was carried out by maintaining the membrane load at 250 g monoclonal antibody/m2; the TMP at 17–20 psi, and the concentration at diafiltration, at 40 g/L. The final, target protein concentration and product recovery method were kept constant. The authors expected that if the cleaning method was effective, the process flux would remain relatively constant. The process flux was calculated by the following equation:

{total permeate volume (L)}/ (total time (h))(filter area).


Figure 5. Total organic carbon content after cleaning
Figure 5 shows that the process flux for the 10 cycles remained fairly constant. The average process flux was approximately 45 LMH, although run four had a lower flux, which may have resulted from the load sample's lower temperature at the start of the experiment (data not shown).


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