Sterilization of Plastic Labware

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A plastic labware that is used repeatedly for experiments needs to be free from any contaminants to ensure a precise result. To ensure this plastic labware are sterilised. In this section different techniques of sterilisation are discussed.
  • Autoclaving : Autoclaving of plastic labware is done at 121°C, 15 psi for half an hour. Before autoclaving process ensure that the caps are properly loosened or removed so as to check any accidental implosion. It has been seen that few chemicals with no appreciable effect on plastic resins at room temperature causes deterioration during autoclaving temperatures. That is why they must be removed with distilled water prior to autoclaving. Resins like Polymethylpentene, PFA, Polypropylene, polypropylene copolymer can be autoclaved repeatedly at 121°C/15 psi with a 15 minutes cycle length. Polysulfone (PSF) and polycarbonate (PC) although autoclavable, but gets weakened on repeated autoclaving. Nylon polyurethane, polystyrene (PS), polyvinyl chloride (PVC), acrylic, LDPE(Low density polyethylene) and HDPE (high-density polyethylene) labware cannot be autoclaved under any conditions.

  • Gas Sterilization : Generally all types of resins can be gas sterilized (ethylene oxide, formaldehyde). Before using the item it is essential to permit a suitable aeration time suited to the particular application.
  • Chemical Disinfectants : Mostly all types of plastics mentioned can be treated to commonly used disinfectants like ethanol, benzalkonium chloride, formalin, iodophors, quaternary ammonium compounds etc. However on prolonged use of an aggressive chemical on less resistant plastics like polycarbonate and acrylic there may be some surface attack.

  • Dry Heat : Some of the resins for which dry heat is advised includes ETFE, PFA, PMP, PSF, and TFE. For example for PSF the maximum temperature applied is 160°C and minimum sterilization time is 2 hours.

  • Microwaving : It has been seen that all plastics permits allow microwaves transmission. Among popular plastic labware PMP and PSF are most transparent to microwaves.

  • Radiation : Gamma irradiation at 2.5 (Mrad) is done with unstable plastic.

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