Esterilizadores for the laboratory

Laboratory sterilizers are units designed to eliminate every form of microbial life present in materials, instruments, culture media or waste, through the controlled application of a sterilizing agent such as saturated steam, dry heat or hydrogen peroxide plasma under validated parameters of temperature, pressure, time and concentration. Saturated steam sterilizers use saturated steam at 121 °C for 15–20 minutes or 134 °C for 3–5 minutes, in a pressurized chamber. The steam releases its latent heat as it condenses on the surface, causing irreversible protein denaturation. It is fast, economical, free of toxic residues and applicable to most heat-resistant materials such as culture media, glassware, instruments, aqueous solutions and biological-infectious waste. Dry heat sterilizers or depyrogenation ovens operate by convection of hot air at 160–180 °C for 1 to 2 hours. They act by oxidation rather than denaturation, which requires higher temperatures and longer times. This is the option for materials that steam would damage or fail to penetrate, such as dry glassware, oils, powders, waxes and sharp instruments. Hydrogen peroxide plasma-phase or low-temperature sterilizers are a low-temperature alternative with no toxic residues, with short cycles and limitations with cellulosic materials and narrow lumens; they are very useful for heat-sensitive materials.