Ethylene oxide (EO) has been used in disinfection and sterilization for a long time and is the only chemical gas sterilant recognized by the world as the most reliable. In the past, ethylene oxide was mainly used for industrial-scale disinfection and sterilization. With the development of modern industrial technology and automation and intelligent technology, ethylene oxide sterilization technology can be safely used in medical institutions to sterilize precision medical devices that are afraid of heat and moisture.

Characteristics of ethylene oxide

Ethylene oxide is the second generation of chemical disinfectants after formaldehyde. It is still one of the best cold disinfectants and the most important member of the four major low-temperature sterilization technologies.

Ethylene oxide is a simple epoxy compound. It is a colorless gas at room temperature and pressure. It is heavier than air and has an aromatic ether smell. Ethylene oxide is flammable and explosive. When the air contains 3% to 80% ethylene oxide, an explosive mixed gas is formed, which burns or explodes when exposed to open flames. The commonly used ethylene oxide concentration for disinfection and sterilization is 400 to 800 mg/L, which is in the flammable and explosive concentration range in the air, so it should be used with caution.

Ethylene oxide can be mixed with inert gases such as carbon dioxide in a ratio of 1:9 to form an explosion-proof mixture, which is safer for disinfection and sterilization. Ethylene oxide can polymerize, but generally the polymerization is slow and mainly occurs in liquid state. In mixtures of ethylene oxide with carbon dioxide or fluorinated hydrocarbons, polymerization occurs more slowly and solid polymers are less likely to explode.

Principle of Ethylene Oxide Sterilization

1. Alkylation

The mechanism of action of ethylene oxide in killing various microorganisms is mainly alkylation. The sites of action are sulfhydryl (-SH), amino (-NH2), hydroxyl (-COOH) and hydroxyl (-OH) in protein and nucleic acid molecules. Ethylene oxide can cause these groups to undergo alkylation reactions, making these biological macromolecules of microorganisms inactive, thereby killing microorganisms.

2. Inhibit the activity of biological enzymes

Ethylene oxide can inhibit the activity of various enzymes of microorganisms, such as phosphate dehydrogenase, cholinesterase and other oxidases, hindering the completion of normal metabolic processes of microorganisms and leading to their death.

3. Killing effect on microorganisms

Both ethylene oxide liquid and gas have strong microbicidal effects. In comparison, the microbicidal effect of gas is stronger, and its gas is generally used in disinfection and sterilization.

Ethylene oxide is a highly effective broad-spectrum sterilant that has a strong killing and inactivation effect on bacterial propagation bodies, bacterial spores, fungi, and viruses. When ethylene oxide comes into contact with microorganisms, but the microorganisms contain sufficient water, the reaction between ethylene oxide and microorganisms is a typical first-order reaction. The dose that inactivates pure cultured microorganisms, the reaction curve is a straight line on the semi-logarithmic value.

Application range of ethylene oxide sterilization

Ethylene oxide does not damage sterilized items and has strong penetration. Most items that are not suitable for sterilization by general methods can be disinfected and sterilized with ethylene oxide. It can be used for the sterilization of metal products, endoscopes, dialyzers and disposable medical devices, industrial disinfection and sterilization of various fabrics, plastic products, and disinfection of items in infectious disease epidemic areas (such as chemical fiber fabrics, leather, paper, documents, and oil paintings).

Ethylene oxide does not damage sterilized items and has strong penetration. Most items that are not suitable for sterilization by general methods can be disinfected and sterilized with ethylene oxide. It can be used for the sterilization of metal products, endoscopes, dialyzers and disposable medical devices, industrial disinfection and sterilization of various fabrics, plastic products, and disinfection of items in infectious disease epidemic areas (such as chemical fiber fabrics, leather, paper, documents, and oil paintings).

Factors affecting the sterilization effect of ethylene oxide

The sterilization effect of ethylene oxide is affected by many factors. In order to achieve the best sterilization effect, only by effectively controlling various factors can it best play its role in killing microorganisms and achieve its purpose of disinfection and sterilization. The main factors affecting the sterilization effect are: concentration, temperature, relative humidity, action time, etc.