laboratory autoclave, an assassin you can trust | Standard operating procedures

by dewi susanti


A laboratory autoclave is a very common device in all the biological and chemical analysis labs. So, what is it? It is a device that kills harmful microorganisms from apparatus, a feature that is of utmost importance especially in research or medical applications. This primary objective is achieved by subjecting its contents to high pressurized steam for long as required period. All microorganisms have an operating temperature which when exceeded, the organism dies. By applying pressurized steam, very high temperatures can be achieved.Medical apparatus are some of the instruments which rely heavily on the laboratory autoclave for their long shelf life.

laboratory autoclave

Apparatus such as glass flasks are repeatedly sterilized in the machine to do a myriad of tests time after time.The standard operating procedures of the sterilizer are explained below:

1. Choose the appropriate containers to use to hold the material. You can either use polypropylene bags, polypropylene containers or stainless steel containers. The bags are the cheapest while the steel containers are the most expensive. However, the bags can get torn and are therefore not used with sharp objects. On the other hand, the polypropylene containers take a long time to autoclave but are cheaper than steel ones. The apparatus should never fill more than two thirds of the containers and they should be vented or not fully capped. This is done to allow steam flow and prevent bursting of the containers due to expanded air.

2. Place the bags or containers in a secondary container. This container should prevent spilling onto the inside of the chamber by containing the spillage. It should have the lowest sides possible, to allow for steam circulation, and should either be polypropylene or a steel container. Household plastics should not be used since they will melt.

3. Load the autoclave. The bags should not touch the autoclave walls and the chamber should not be overfilled. An indicator is usually used to gauge the completion of the test based on the temperature of the chamber and the time it has stayed in it. The indicator types are physical, chemical or biological. Chemical indicators are the most common and are usually used. Commercially available chemical indicators feature a strip of autoclave tape that contains markings that changes color once the appropriate conditions have been achieved.

4. Close and secure the autoclave door, then start it.It is important to observe utmost care when unloading the apparatus from the autoclave. Wear protective material such as heat insulated gloves and don’t open the autoclave unless the internal pressure is indicated to be zero. Release the steam by opening the door slightly. Leave the door fully open for about ten minutes before taking the containers, which will still be hot, out. Once the apparatus is out, let the liquids stand for about 20 minutes without opening the containers to avoid personal injury from super heated liquids. Once open, you have clean, microbe free apparatus.The laboratory autoclave should be operated by trained personnel to avoid damage and personal injury.

Preventive maintenance should also be carried out time after time to ensure optimum operation. In addition, a biological spore test should be performed regularly and the autoclave should only be used after the spore test is passed. Failure to do so undermines the validity of the instruments sterilized. Conquer the procedure outlined above and the assassin is yours.