Sterilization, membrane

Filtration =s0.22,um pore size, sterile membrane filter... 

Membrane filtration is the technique reeommended by most pharmacopoeias and involves filtration of fluids through a sterile membrane filter (pore size = 0.45 im), any microorganism present being retained on the surfaee of the filter. After washing in situ, the filter is divided aseptically and portions transferred to suitable culture media which are then incubated at the appropriate temperature for the required period of time. Water-soluble solids can be dissolved in a suitable diluent and processed in this way. 

Sterile membrane filtration unit with 47 mm diameter... 

Aseptically decant the Tween solution, splitting the total volume present equally among each of four sterile membrane filter holders. 

Use unsterilized medium and filter the medium through the normal sterilizing membrane hooked directly to the filing equipment. The media may be prefiltered to reduce bioburden and increase filtration efficiency. 

Sterility Membrane filtration methodologies do not always correlate to in vivo. Indicator of microbial contaminants... 

Keep the suspension at room temperature for 2 h (or overnight at 4°C). In order to limit the maximum diameter of the liposomes for intravenous injection, the suspension can be filtered using sterile membrane filters with 3.0-pm pores (Millipore). 

Membrane filtration application to biopharmaceutical product development is extremely important since sterile protein-peptide products can only be prepared via sterile filtration and gamma radiation steam cannot be used under pressure. There are several excellent works in the field of sterile membrane filtration.34-36 The filter media most often tested for protein formulations with minimum adsorption and maximum compatibility are mixed esters of cellulose acetate, cellulose nitrate, polysulfone, and nylon 66. Membrane filters must be tested for compatibility with the active drug substance and selected for formulations if they have the lowest adsorption and maximum compatibility with the product. 

Sterilization. Sterility Is a necessary requirement for all membrane devices used clinically, and the sterilization procedure must not change the functional or blocompatlble character of the device. Sterility, the condition of absolute absence of viable life forms, can be achieved by physical (heat. Irradiation) or chemical means. Chemicals used to sterilize membrane devices may be either gaseous (ethylene oxide) or liquid (formaldehyde, peroxides, hypochlorite) In nature. The generally accepted... 

Place the sterile membrane on agar (best when a few days old) with blunt tweezers and turn over when thoroughly wet so that the marked side is up. 

Chill plates for 1 h at 4°C and number dry, Triton-free nitrocellulose membranes and sterilize membranes as in step BI. 

To assess microbial rejections, sterile membranes were challenged with P. diminuta, B. coagulans, S. cerevisiae, and P. roqueforti spores suspended in apple puree or 0.1% peptone. Reductions achieved by ultrafiltration of cells in peptone at normal operating pressure (300 psi) were 5.1, 6.0, 7.6, and >9.0 logs for smallest to largest organisms (Table III). 

Clean, sterilized, membrane-covered electrodes are inserted into the chamber. 

Swabbing is a technique in which a surface is lightly scrubbed with a moistened collector (swab), most often a cotton or alginate bud. The swab is then rolled over the surface of an agar plate. Alternatively the swab may be immersed in a liquid aiKl agitated to suspend the microorganisms collected. The liquid is then plated, or passed through a sterile membrane filter and plated on a nutrient medium. 

Products which can not be sterilized by heat in their final container must be subjected to sterile filtration on a sterile membrane filter with a pore size of 0.2 micrometer or on an equivalent filter. If necessary and possible, the product in the final container must be subjected to a microbial reducing treatment. 

A very common commercial device for hemodialysis is the C-DAK 4000 artificial kidney of Althin CD Medical, Inc. (acquired by Baxter International, Inc. in March, 2000). This disposable, sterilized membrane module, shown in Figure 19.5, resembles a shell-and-tube heat exchanger. The tubes, which number 10,000, are hollow fibers, 200 microns i.d. by 10 microns wall thickness by 22 cm long, made of hydrophilic microporous cellulose acetate of 15 to 100 A pore diameter. Alternatively, fibers of polycarbonate, polysulfone, and other poly-... 

In the membrane filter process, larger quantities of water can be pressed or sucked through a sterile membrane filter inserted in the sterile filtering device. The filter is then stretched free of bubbles on the surface of the soldified nutrient medium in a Petri culture dish and the culture thus... 

Sterilized membrane filters, to fit the filter unit, pore size 0. 3 pm... 

The prepared and sterilized membrane-filter unit is connected to the... 

Pipettes, 100 ml and 50 ml, sterilized membrane filter, pore size 0.6 pm, forceps, burner for flaming, writing instruments... 

Sterilization of solutions, such as fermentation broths, containing thermally labile compounds is accomplished by sterile filtration. This requires the use of sterile membranes of porosity of <0.45 pm and a previously sterilized filter housing and flasks. Filter housings and clamps should be packaged prior to autoclaving and not opened until use. One may purchase special autoclavable wrappings of various sizes for this purpose alternatively, aluminum foil is frequently used. 

Certain products that cannot be terminally sterilised may be subjected to an aseptic filtration procedure [11] using a satisfactory sterile membrane filter membrane, tightly fixed in a filter holder. The operator passes the liquid product through a sterile and bacteria retentive membrane, mostly with a nominal pore size of 0.2 pm or smaller. Such membrane filters can capture most bacteria, yeasts and fungi, but not all viruses and mycoplasms. The liquid should be asepti-cally collected in a sterilised dedicated clean container directly after sterile filtration. 

For the filtration of small volumes (up to 100 mL), generally a small disposable ready-to-use sterile membrane filter unit is used. The diameter of these filters is usually 25 mm or more. They are sterile and free of endotoxins, packed individually, have a low dead volume, and are dedicated for single-use (see Fig. 30.11). 

Filtration systems used for sterilization (membrane filters) can be used to separate cells from the supernatant but only for relatively small volumes as they do rapidly become clogged, and for this sort of volume centrifi ation is usually easier but not as efficient at removing small cell debris. Tangential flow filtration is used to reduce problems of filter blockage by continuous recirculation of the suspension across the membrane, and is recommended for larger volumes (several litres). Low volume systems are available from recognized filtration suppliers (e.g. Millipore, Sarstadt, Pall). Filtration systems have been reviewed (43). 

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