Biomedical Engineering Reference
In-Depth Information
mixed and dissolved. The unique M*Bag is made of a multilayer laminated
clear plastic designed to provide high mechanical strength. A large screw
cap port allows powders or other solids to be easily poured into the bag.
Probes to measure pH and conductivity can be inserted. A large outlet port
allows the M*Bag to be drained completely.
Standard systems are available for 20 and 50 L bags. These can be used
to mix volumes from 1 to 35 L of liquid. Larger systems up to 500 L liquid
volume are available. The WAVE Mixer principle has also been used for the
mixing of materials in custom-shaped rigid containers.
Biological and particle contaminants present in buffers can have a large
impact on process efficiencies and final product quality. Therefore, nor-
mal flow filtration is one of the first steps (after dissolution) in any buffer
preparation process. Buffer filtration is key to protection of chromatography
columns and ultrafiltration operations and to the production of an endo-
toxin-free final product. Buffer filtration also aligns with FDA guidelines on
sterile drug products that advise to reduce and control the bioburden across
the process.
Buffer filters should be chosen based on the following characteristics:
• Validated retention of bacteria
• Broad chemical compatibility
• High permeability
• Physical robustness
For filtration of sterile and reduced-bioburden buffers, GE Healthcare offers
ULTA™ Pure SG (for buffer sterilization) and ULTA Prime CG (for biobur-
den reduction). The ULTA family of filters uses membranes with industry-
leading permeability that consistently outperforms competitive offerings.
Both filter grades are constructed using a polyethersulfone 0.2 micron mem-
brane, which is physically robust and chemically resilient, so they perform
reliably regardless of the buffer being prepared. Additionally, both filters
employ a final membrane that is validated for bacterial retention using the
ASTM F838-05 methodology (LRV > 7 for ULTA Pure SG and LRV > 5 for
ULTA Prime CG). ULTA filters are available in a wide variety of cartridge
and capsule formats with surface areas ranging from 450 cm
2
to 1.5 m
2
in a
single device.
Fluid Management
Once prepared, buffers are transferred to downstream processing stations
when using larger volumes, on carts; or else through a tubing system with
