Recommended autoclave cycle is 121°C, 15 psig (1 bar) for 20 minutes.All items should be carefully cleaned before autoclaving to prevent baking contaminants onto the surface of the plastic. After cleaning, all items should be rinsed thoroughly in distilled water before autoclaving. Certain chemicals which have no appreciable effect on plastics at room temperature may cause deterioration at autoclaving temperatures and therefore must be removed.
Do not autoclave containers (except those made of fluoropolymers) containing detergent or wetting solutions.
- Before autoclaving, just set cap or closure on top of the container without engaging the threads. (If this is not done, pressure differentials may cause containers to collapse during autoclaving.)
- For best results, use a slow exhaust cycle.
- Carboys with spigots must always be autoclaved empty (the spigot may leak during the autoclave cycle).
Plastics transfer heat more slowly than glass or metal and may take longer to reach sterilizing temperatures in the autoclave. Because of differences in heat transfer characteristics between plastics and inorganic materials, the contents of plastic containers may take longer to reach sterilization temperature (121°C). Therefore, longer autoclaving cycles are necessary for liquids in large-volume plastic containers. Adequate cycles can be determined only by experience with specific liquids and containers.
- Chemical additives in steam will attack transparent plastics and cause a permanently glazed surface after autoclaving.
- Some transparent plastics may absorb minute amounts of water vapor and appear cloudy after autoclaving. The clouding will disappear as the plastic dries. Clearing may be accelerated in a drying oven at 110°C.
- Use polypropylene copolymer (PPCO) bottles instead of polysulfone with Tween in the autoclave.
- Test tube racks filled with tubes must be autoclaved on a flat surface.
Specific Plastic Considerations
Polypropylene, polymethylpentene, polypropylene copolymer, TEFZEL ETFE, TEFLON FEP, and PFA may be autoclaved repeatedly at 121°C, 15 psig. Cycles should be at least 15 minutes to ensure sterility.
Polycarbonate products are autoclavable. They must be thoroughly rinsed before autoclaving because detergent residues cause crazing and spotting. Autoclaving cycles should be limited to 20 minutes at 121°C. PC shows some loss of mechanical strength after repeated autoclaving and therefore may not function well under high-stress applications, such as centrifugation. Our PC vacuum chambers are considered "not autoclavable" for this reason.
Do not use strong alkaline detergents on polycarbonate. Do not use boiler steam containing alkaline chemical additives that may attack the plastic and cause the item to fail.
Acetal products are autoclavable at recommended settings. Proper ventilation is required as acetal will emit formaldehyde odor during autoclaving. The following statement complies with the California Safe Drinking Water and Toxic Enforcement Act of 1986: "WARNING: Upon autoclaving, this product may release formaldehyde, a chemical known to the State of California as a carcinogen."
Polysulfone products are autoclavable. They are somewhat weakened by repeated autoclaving, although less than polycarbonate. If autoclaved repeatedly, polysulfone products will eventually fail under high-stress applications, such as high-speed centrifugation.
NALGENE PVC Tubing can be autoclaved, but ethylene oxide or chemical disinfectant is preferred. If you autoclave it, follow these guidelines:
Clean and rinse tubing thoroughly, including final rinse with distilled or deionized water. Coil tubing loosely and keep ends open. Wrap in muslin or linen; tape or tie loosely. Place on a nonmetallic tray in the autoclave so wrapped tubing is not touching wall or rack of autoclave. Do not stack anything on the tubing. Use 15 minute cycle at 121°C, 15 psig. Restore clarity of tubing by drying approximately 2 hours at a temperature no higher than 75°C.
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