Sterilizing filters

Adsorption of t-PA to process equipment surfaces consisting of either stainless steel or glass was minimized by adding the detergent polyoxyethylene sorbitan monooleate (Tween 80) to the semm-free culture conditioned media at 0.01% (vol/vol). The equipment was also rinsed, before use, with phosphate buffered saline (PBS) containing 0.01% Tween 80. Hydrophilic, plastic equipment was used whenever possible. AH buffers were sterile filtered. Sterile filtration of Hquids and gases is usually carried out using 0.2 or 0.45 p.m filters. 

The first two categories, clarifying and crossflow filters, have been very well developed and optimized for use in biotechnology and standard wastewater treatment applications. Equipment is easily available for these applications, whether as small 0.2 micron sterilizing filter used to terminally sterilize 100 ml of product solution, or a small 500 ml crossflow filter used to concentrate a small amount of antibody solution. Many vendors of this equipment to wastewater treatment applications have their origins in the CPI (Chemical Process Industries), and have incorporated many of the scale-up and optimization properties developed in much larger units used in large scale chemical production. As a result, these two filtration unit operations are one of the most optimized and efficient used in wastewater treatment. 

If air is bled back into the vessel it should be passed through a sterilizing filter. 

Drying or cooling. Dressings packs and other porons loads may become dampened during the sterilization process and mnst be dried before removal fiom the chamber. This is achieved by steam exhanst and application of a vacnum, often assisted by heat from the steam-filled jacket if fitted. After drying, atmospheric pressure within the chamber is restored by admission of sterile filtered air. 

An example of the second method of parenteral suspension preparation is testosterone suspension. Here, the vehicle is prepared and sterile-filtered. The testosterone is dissolved separately in acetone and sterile-filtered. The testosterone-acetone solution is aseptically added to the sterile vehicle, causing the testosterone to crystallize. The resulting suspension is then diluted with sterile vehicle, mixed, the crystals allowed to settle, and the supernatant solution siphoned off. This procedure is repeated several times until all the acetone has been removed. The suspension is then brought to volume and filled in the normal manner. 

Mix the reduced A-chain solution with activated antibody solution at a ratio of 2mg of antibody per mg of A chain. Sterile filter the solution through a 0.22 pm membrane, and react at room temperature under nitrogen for 18 hours. 

Furthermore, the transplants are often packed in aluminum boxes, which are sealed by sterile filters permeable to water vapor. Even if the box can be designed with a negligible resistance to water vapor flow, the heat transfer is substantially reduced. 

The culture medium was prepared by dissolving all the compounds for the culture medium except L-threonine in an Erlenmeyer flask containing 5 L of water. The pH was adjusted to 5.5 with NaOH and then sterilized for 20 min at 120 °C. L-Threonine was filtered (syringe sterile filter Sartorius Minisart 0.2 pm) and was added to the sterilized culture medium. 

After 10-12 days, the maximum product concentration was achieved and fluvastatin completely consumed. The 6-hydroxy-fluvastatin-containing culture liquid was stored in the Wavebag at —20 °C for later purification. In other cases, the culture liquid was conveniently and safely harvested from the Wavebag without aerosol formation by sucking into glass bottles in a vacuum line with a sterile filter installed between the collecting vessel and the vacuum pump. 

The filling mandrels are comprised of a set of filling tips which are held within a protective air shower this is a small area within the filling machine which is typically fed with sterile filtered air. When the molds are beneath the air shower, the filling tips are lowered into the neck of the partially formed container and the containers are filled. The mandrels return to the protective air shower, and the containers are sealed... 

As already stated, for aseptic BFS, the container is filled in a localized air shower provided with sterile filtered air. However, there is a short period of time between container formation and filling, when the open container is transferred from the par-ison formation position to the filling position and exposed to the clean room environment. During this shuttling period, there is a possibility for contaminants from the room environment to enter the container. The air used to form the parison (parison support air) is typically sterile filtered air. If this is not the case, it is also possible for nonsterile air to enter the parison during parison formation. 

Buffer filtration device (either a glass filtration unit, fitted with a 0.45-itm membrane, connected to a side-arm flask or a tissue culture sterilization filter unit). 

Unfractionated Preparatioii. Each harvest of the enzyme was concentrated to 401 and diafiltered with 0.01 M sodium acetate, pH 6.0. Enzyme concentrate was bound to Q-Sepharose and eluted with 0.4 M sodium acetate, pH 6.0. Fractions with activity were pooled, sterile filtered and stored in the cold in 10 mM veratryl alcohol. Before further purification, the solution was dialyzed. 

To study the effect of veratryl alcohol, purified lignin peroxidase or unfractionated enzyme preparation was incubated with buffer, pH 3.0 or 5.0. The concentration of veratryl alcohol in the incubation mixture was 0, 10 or 100 mM. Incubation times were 38 days at 20°C and 40 days at 4°C. The protein concentration of purified enzyme was 80/tg/ml and of unfractionated preparation 180 tg/ml. The incubation mixtures were sterile filtered to prevent microbial growth. 

Pass the suspension through a syringe filter (0.45 pm sterile filter) to remove the gel, add an equal volume of a saturated solution of phenol in 0.3 M NaOAc pH 5.2, and vortex hard. 

If possible, media should be sterilized in situ. In-line sterilizing filters for routine addition of gases, media, acids or alkalis, defoaming agents, etc., to fermenters should be used where possible. 

Buffers containing sodium (hydrogen) carbonate are not allowed to be autoclaved. These buffers have to be sterile filtered through a 0.2-pm filter. 

Fill washed and dried glassware with sterile filtered water, sonicate for 5 minutes and test with a particle counter. 

Perform a pressure hold test with the nonsterilized filter. Expose the filter to the chosen sterilization conditions. Repeat the pressure hold test with die sterilized filter. For pressure hold test conditions, follow the recommendations of the filter supplier. 

Perform a pressure hold test with the sterilized filter. Perform the filtration of the product to be sterile filtered using normal production conditions. After the filtration step, the filter should be tested again with the bubble point test. 

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