Laboratory
Autoclave
Gufusæfir er í daglegu tali kallaður átóklafi (autoclave) og er ómissandi tæki á rannsóknastofum þar sem nauðsynlegt er að dauðhreinsa verkfæri, æti eða úrgang svo eitthvað sé nefnt.
An autoclave sterilises liquids, glassware etc. using heat and pressurised steam. They are generally used in labs where personnel are working with biospecimens, microorganisms and biological agents, as well as where sterile drugs or chemicals are needed as catalysts for certain chemical reactions.
Autoclaves are available in many different types and sizes, depending on the materials they are designed to sterilise. The simplest version is a pressure cooker: a closed vessel with water in the bottom where heat produces pressurised steam. A laboratory autoclave works basically in the same way as a pressure cooker, but is larger and has a wider range of settings. In fact, it is not unusual to see pressure cookers used in labs for smaller tasks that require less precision.
It is standard practice to sterilise at 121°C for 15 minutes. Under these conditions, the pressure inside the chamber reaches around 1 bar, which is enough to kill almost all organisms, but there are a few important exceptions. The spores of some types of microorganism can survive sterilisation and prions also withstand sterilisation. Something to keep in mind when selecting a sterilisation method:
- Glassware.
- Metal instruments, e.g. knives or syringes that need to be sterilised.
- Plastic that can withstand heat and pressure, for example Polypropylene (PP) and Teflon.
- Plastic that cannot withstand heat and pressure, such as Polystyrene (PS).
- Corrosive chemicals, acids and alkalis.
- Flammable chemicals, methanol, ethanol, chloroform or phenol.
- Radioactive materials
It is recommended that you use only borosilicate glassware, i.e. Pyrex or Kimax, since these materials are designed to withstand high temperatures and pressure.
Lids and stoppers must not be tightly screwed onto flasks or other containers. Air must be able to pass through – otherwise the containers will explode.
Containers without lids should be closed with aluminium foil in order to keep the insides sterile after they are removed from the autoclave. In this way, you can keep a container sterile for a long time.
Before loading objects into the autoclave, you must stick on some sterilisation indicator tape. This is special striped tape – the stripes change colour when exposed to high temperatures, usually turning black or blue at around 120°C. This tells you that the cycle has worked properly.
Do not run a cycle until you have made sure that the autoclave is securely closed and checked all the safety locks. Take care when opening the autoclave after the cycle is complete (it is a good idea to wait 10 minutes). Keep your face and hands away from the door to avoid contact with hot steam. Wear gloves and safety goggles.