A variety of laboratory processes require sterile containers. If you’re using laboratory plasticware, it is important to consider several factors before the container is placed in an autoclave.
Here are 6 questions to ask before autoclaving plastic bottles:
1) Is your plastic bottle suitable for autoclaving?
Not all plastic polymers are suitable for autoclaving, for example, you should not autoclave plastic bottles made from either Low Density Polyethylene (LDPE) or High Density Polyethylene (HDPE). These polymers have a narrow temperature range of between -50 to +80°C in the case of LDPE, and while HDPE offers a wider range of between -100 to +120°C, it is still below 121°C which is most commonly used for autoclaving. Other polymers that are not suitable for autoclaving include Polymethylmethacrylate, Acrylic (PMMA), Polystyrene (PS) and Polyvinylchloride (PVC), again because of their narrow temperature ranges
It is safe to autoclave plastic bottles made from Polypropylene (PP), Polytetrafluoroethylene (PTFE), Polyfluoroalkoxy (PFA), Polymethylpentene (often abbreviated to PMP or TPX) and Polycarbonate (PC) as these polymers are stable at higher temperatures.
2) Has the plastic bottle been cleaned beforehand?
Before you autoclave the plastic bottle, it is important to ensure the container has been cleaned. This will prevent any contaminant substances from baking onto the surface of the plastic bottle during the process.
3) Are the caps completely loose?
Before autoclaving plastic bottles it is vital that caps have been completely removed. Even a loosely screwed cap can result in a vacuum being created within the bottle during the autoclave process. This will cause the plastic bottle to collapse and distort, rendering it unusable. Instead, you must completely detach the cap from the bottle itself before it is placed in the autoclave. One approach that is commonly used is to tape the cap to the side of the container neck using autoclave tape, this ensures the correct cap and bottle remain together during the process.
4) Is there room for steam to circulate in the autoclave?
You should avoid over-stacking the autoclave as this will stop the steam circulating between the items effectively and could jeopardise the sterilisation process. Instead, ensure that there is plenty of room between items. This is particularly important with autoclaving plasticware, as plastic polymers transfer heat more slowly than glass or metal. Plastics can also take longer to reach sterilisation temperatures, so ensuring steam can circulate freely within the autoclave is even more important.
5) Have you validated your autoclave?
White the standard autoclave temperature is 121°C, its essential to regularly calibrate your autoclave to ensure the visible temperature displayed is correct. Its also important to check the specific instructions associated with your autoclave to determine cycle times.
6) Has sterilisation been achieved?
It is important to ensure sterilisation has ben successfully attained. Before autoclaving plastic bottles, its advisable to use an indicator to demonstrate that the correct temperature has been consistently achieved. Using autoclave tape or other forms of physical indicator (many of which visibly change appearance of colour after having been subjected to the temperatures associated with lab sterilisation) can provide clarity on whether the process has worked.
All blog information was provided courtesy of DWK
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