Which of the following is NOT a method of sterilization?

Sterilization is a process that eliminates all forms of microbial life, including bacteria, viruses, spores, and fungi. The methods listed include steam/moist heat, low-temperature gas plasma, and radiation, all of which are proven techniques for achieving sterilization.

Steam/moist heat, commonly known as autoclaving, uses high-pressure steam to kill microorganisms, including resistant spores, making it a reliable method of sterilization. Low-temperature gas plasma utilizes hydrogen peroxide in a gaseous form to achieve sterilization and is particularly useful for heat-sensitive instruments. Radiation sterilization, often using gamma rays or electron beams, disrupts the DNA of microorganisms, effectively ensuring their destruction.

Filtration, however, is primarily a method of separation. While it can effectively reduce microbial load in liquids or gases by physically trapping them, it does not typically guarantee the complete elimination of all microbial life, especially if the pores of the filter become clogged or if a filter with insufficient pore size is used. Thus, filtration is not classified as a method of sterilization in the same way that the other methods mentioned are.