What is the typical concentration for alkali sterilization?
Thread Content
What is the typical concentration for alkali sterilization?
There are physical, chemical, and biological methods, but biological methods use biological agents to eliminate pathogens; they work slowly and do not provide thorough sterilization, so they are generally not used for disinfecting areas affected by infectious diseases. Therefore, physical and chemical methods are primarily employed for disinfection. (1) Physical disinfection methods 1. Mechanical disinfection Generally, washing with soap and rinsing under running water can eliminate most or even all bacteria from the hands; using multiple layers of masks can prevent pathogens from being expelled or entering through the respiratory tract. Using filters in ventilation systems can maintain a sterile condition of the air in operating rooms, laboratories, and isolation wards. 2. Thermal disinfection Includes burning, boiling, flowing steam, high-temperature steam, dry heat sterilization, etc. It can cause pathogen proteins to coagulate and denature, thereby losing their normal metabolic functions. (1) Burning This method can be used for pollutants of low economic value, as well as metal instruments and corpses. Simple, economical, and provides stable results. (2) Boiling This method is used for items that can withstand boiling as well as ordinary metal instruments; disinfection is achieved in 1–2 minutes at 100°C, but spores require a longer time. Anthrax spores need to be boiled for 30 minutes, tetanus spores require 3 hours, and botulinum spores need 6 hours. For the disinfection of metal instruments, adding alkaline agents such as 1–2% sodium carbonate or 0.5% mild soap can dissolve fats and enhance the bactericidal effect. Adding 1% soapy water at a rate of 15 l/kg to cotton fabrics has the effect of disinfection and degreasing. When boiling items for disinfection, do not fill the container more than 3/4 full; the items should be submerged under water. Make sure there are gaps to facilitate convection. (3) Mobile steam disinfection: With a relative humidity of 80–100% and a temperature of around 100°C, water vapor condenses on the surface of objects, releasing heat energy to kill pathogens. And when negative pressure is generated due to the condensation and contraction of steam, it facilitates the entry of outer-layer hot steam for replenishment, allowing it to penetrate deep into the items, thus accelerating heat transfer and promoting disinfection. (4) Autoclaving: The typical pressure is 98.066 kPa, and the temperature ranges from 121 to 126°C; bacteria spores can be completely destroyed in 15 to 20 minutes. This method is suitable for heat-resistant and moisture-sensitive items. (5) Dry heat sterilization Dry heat has poor heat conduction, low heat capacity, and weak penetration, resulting in slower heating of objects. A temperature of 160–170°C and 1–2 hours are required for sterilization. Suitable for glass containers that cannot hold moisture, metal instruments, etc. The heat tolerance of different pathogens is expressed in terms of heat death time. 3. Radiation disinfection There are two types: non-ionizing radiation and ionizing radiation. The former includes ultraviolet light, infrared light, and microwaves, while the latter consists of high-energy electron beams such as gamma rays (cathode rays). Infrared and microwaves mainly rely on heat generation for sterilization. Ionizing radiation equipment is expensive and can cause certain harm to items and the human body, so it is used less frequently. Ultraviolet light is the most commonly used method at present; it can cause changes in cellular components, particularly nucleic acids, cytoplasmic proteins, and acids, leading to the death of microorganisms. The wavelength range of ultraviolet light is 2100–3280 Å; the wavelengths that are effective in killing microorganisms lie within the range of 2000–3000 Å, with the strongest effect occurring at wavelengths of 2500–2650 Å. Fungal spores have the strongest resistance to ultraviolet light, followed by bacterial spores, with bacterial vegetative cells having the weakest resistance, with only a few exceptions. Ultraviolet light has poor penetration; those with a wavelength of 3000 Å or less cannot pass through 2 mm thick ordinary glass. Dust in the air and relative humidity can reduce its bactericidal effect. The penetration ability into water decreases with depth and turbidity. However, due to its ease of use and lack of damage to medicines, it is widely used for disinfecting surfaces of air and ordinary items. Irradiating the human body can cause skin erythema, ultraviolet keratitis, and ozone poisoning, among other effects. Therefore, users should avoid it or take appropriate protective measures when using it. Sunlight also relies on ultraviolet rays, but due to scattering and absorption in the atmosphere, only 39% reaches the ground; therefore it is suitable only for microorganisms with low tolerance and requires prolonged exposure. Furthermore, apart from laboratory applications, air filtration is only applicable in buildings with ventilation systems; therefore, it is difficult to use it for general disinfection tasks. (II) Chemical disinfection methods
Based on their effects on pathogen proteins, they are classified into the following categories. 1. Coagulating protein disinfectants include phenols, acids, and alcohols. (1) Phenols Mainly include phenol, lysol, hexachlorophene, etc. It has a distinctive odor, and its bactericidal effect is limited. It can cause textiles to change color and rubber products to become brittle; it also has a certain irritating effect on the skin. Therefore, apart from lysol, it is rarely used. Phenol (carbolic acid): a colorless crystal with a distinctive odor; it turns pink when exposed to moisture, but its disinfecting power remains unchanged. It is a protoplasmic poison for cells; at a concentration of 1:80 to 1:110, it can kill bacterial vegetative forms at 20°C within 30 minutes. However, it cannot kill spores or viruses with strong resistance. Adding soap can saponify fats, dissolve proteins, enhance penetration, and strengthen the disinfecting effect; however, it is highly toxic, irritating to the skin, and has an unpleasant odor, so it cannot be used for skin disinfection. Lysol (phenolic soap solution): It is made from 47.5% cresol and potassium soap. Red-brown in color, soluble in water, it has cleaning properties; its bactericidal power is 2 to 5 times greater than that of carbolic acid. It is commonly used as a 2–5% aqueous solution, and can be applied by spraying, wiping, soaking containers, and for hand washing. Bacterial vegetative forms can be killed within 10–15 minutes; however, its effectiveness against spores is poor. Hexachlorophane: It is a biphenol compound that is slightly soluble in water but readily soluble in alcohols, esters, and ethers; the addition of alkali or soap can enhance its solubility. It has low toxicity and irritation, but it possesses strong bactericidal properties. It is mainly used for skin disinfection. Washing hands with 2.5–3% hexachlorophene soap can reduce skin bacteria by 80–90%; however, there are reports of it causing nerve damage, so its long-term use is not recommended. (2) Acids They have a killing effect on both bacterial vegetative cells and spores. However, it can damage items, so it is generally not used for disinfecting living spaces. 5% hydrochloric acid can be used to disinfect tableware and fruits; adding 15% salt to a 2.5% solution can be used to disinfect fur and leather, by soaking them at 30°C for 40 hours per 10 liters of solution. Lactic acid is commonly used for air disinfection; fumigating a space of 100 m3 with 10 g of lactic acid for 30 minutes is sufficient to kill staphylococci and influenza viruses. (3) Alcohols: Ethanol (alcohol) – A 75% concentration can rapidly kill bacterial reproducing forms; it has a slower effect on ordinary viruses, its effect on hepatitis viruses is uncertain; it has a certain killing effect on fungal spores, but no effect on spores. Used for skin disinfection and soaking disinfection of thermometers. Since it cannot kill spores, it cannot be used for soaking and disinfecting surgical instruments. Isopropyl alcohol has a bactericidal efficacy of over 2. Protein-dissolving disinfectants are mainly alkaline substances, with sodium hydroxide and lime being commonly used. (1) Sodium hypochlorite: A white crystal that is highly soluble in water and possesses strong bactericidal properties. A 2–4% solution can kill viruses and bacterial forms, while a 10% solution can eliminate Mycobacterium tuberculosis. A 30% solution can destroy spores within 10 minutes. Due to its strong corrosive nature, it is used very rarely, only for eliminating anthrax spores. (2) Lime: When exposed to water, it generates high heat and dissolves proteins, thereby killing pathogens. A 10–20% lime milk solution is commonly used to disinfect excreta; the amount used should be twice that of the excreta. After mixing, it is left to act for 4–5 hours. 20% lime milk is used to disinfect areas contaminated with anthrax, applied every 4–6 hours for 2–3 consecutive times. Painting the walls twice can kill Mycobacterium tuberculosis spores. Due to its unstable nature, it should be prepared fresh at the time of use. 3. Oxidizing protein disinfectants Include chlorine-based disinfectants and peroxide-based disinfectants. Due to its strong disinfecting power, it is currently the most widely used in medical and epidemic prevention efforts. (1) Bleaching powder Most widely used. Its main component is calcium hypochlorite, with an active content of 25–30%. It is unstable and can be decomposed by light, heat, moisture, and CO2. Therefore, it should be stored in a sealed container in a dark and dry place for no more than 1 year. The active ingredient, hypochlorous acid, can penetrate into cells, oxidize the sulfhydryl groups of cellular enzymes, and disrupt cytoplasmic metabolism. It has strong and rapid bactericidal effects in acidic environments; at high concentrations, it can kill spores. In powder form, it is used for disinfecting feces, sputum, pus, etc. Add 200 grams of dry powder per liter, stir well, and let it sit for 1–2 hours. For urine, add 5 grams of dry powder per liter and let it sit for 10 minutes. The 10–20% emulsion, in addition to disinfecting excreta and secretions, can be used to spray toilets, contaminated vehicles, etc. If stored for a long time, the actual effective chlorine content should be measured to adjust the dosage used in preparation. The powder and tablets of bleaching powder contain 60–70% available chlorine; the amount used can be reduced proportionally. (2) Chloramine-T: It is an organic chlorine disinfectant containing 24–26% available chlorine; it is relatively stable, and when stored in a sealed container for 1 year, only 0.1% of its available chlorine is lost. Slightly soluble in water (12%), with low irritancy and corrosivity; its action is slower than that of hypochlorous acid. 0.2% can kill bacterial vegetative forms within 1 hour, 5% can kill Mycobacterium tuberculosis within 2 hours, while it takes more than 10 hours to eliminate spores. Various ammonium salts can enhance its bactericidal effect. 1–2.5% solutions are also effective against hepatitis viruses. The active liquid must be prepared 1–2 hours before use; if left for too long, its bactericidal effect is reduced. (3) Sodium dichloroisocyanurate, also known as Hypochlorite, is a widely used organic chlorine disinfectant with a chlorine content of 60–64.5%. It has advantages such as high efficiency, broad spectrum of activity, stability, high solubility, and low toxicity. Aqueous solutions can be used for spraying, soaking, or wiping; dry powder can also be used to disinfect contaminants directly, as well as to treat feces and other excreta, with a usage method similar to that of bleach. Spray directly on the ground at a rate of 10–20 g/m2. When mixed with polyformaldehyde powder and ignited, the gas can be used for fumigation disinfection. It can be mixed in a 1:4 ratio with coagulant No. 92 (synthesized from aluminum hydroxide chloride along with iron powder, sulfuric acid, hydrogen peroxide, etc.) to create \"Yu Shui Qing\", which is used for disinfecting drinking water. It can also be combined with sodium sulfonate to produce various disinfecting detergents, such as Dijingmei and Uochujing. It has a killing effect on hepatitis viruses. In addition, trisodium chlorophosphate and dibromocyanuric acid have similar effects. (4) Peracetic acid, also known as peroxyacetic acid, is a colorless and transparent liquid that is volatile and has an irritating acidic odor. It is a highly effective disinfectant that dissolves easily in water and organic solvents such as ethanol. It possesses bleaching and corrosive properties; its stability is low, as it decomposes easily when exposed to heat, organic substances, heavy metal ions, or strong bases. 0.01–0.5%; it can kill bacterial vegetative cells within 0.5–10 minutes, and spores can be killed at a concentration of 1% after 5 minutes. The commonly used concentration is 0.5–2%. Disinfection can be carried out by immersion, spraying, or wiping. Under sealed conditions, disinfection can also be achieved through aerosol application (at a concentration of 5%, 2.5 ml/m2) or fumigation (at a concentration of 0.75–1.0 g/m3). (5) Chlorine dioxide: A 3–6% solution can achieve disinfection in 10 minutes. 10–25% for 60 minutes; it can achieve sterilization and is used for disinfecting heat-sensitive plastic products, tableware, clothing, etc. 10% hydrogen peroxide gas deep-spray disinfection of contaminated surfaces in rooms ； 180–200 ml/m3; can kill bacterial vegetative cells within 30 minutes ； 400 ml/m3; spores can be killed in 60 minutes. Ethanol, when absorbed through the lungs, can cause **, but it causes no damage to the skin and can be used as a substitute for ethanol. (6) Potassium permanganate: Soaking at a concentration of 1–5% for 15 minutes can kill bacterial vegetative forms. It is commonly used for disinfecting tableware and fruits/vegetables. 4. Cationic surfactants Primarily quaternary ammonium salts; at high concentrations, they coagulate proteins, while at low concentrations, they inhibit bacterial metabolism. It has a bactericidal concentration, low toxicity and irritation, no bleaching or corrosive effects, is odorless, stable, and has good water solubility. However, its bactericidal power is weak, especially against spores; it is greatly affected by organic substances, and has many incompatible combinations, which are its disadvantages. In China, chlorhexidine, domiphen, and disinfectant are produced domestically; among them, domiphen has a strong bactericidal effect. The commonly used concentration is 0.5–1.0‰, and it can be used to disinfect skin, metal instruments, tableware, etc. It is not suitable for disinfecting excreta and secretions. 5. Alkylation disinfectants (1) Formalin It is a 34–40% solution of formaldehyde and possesses a strong bactericidal effect. A 1–3% solution can kill bacterial vegetative forms, while a 5% solution can eliminate spores within 90 minutes. For fumigation disinfection in indoor areas, a concentration of 20 ml/m3 mixed with an equal amount of water is typically used for 10 hours; to eliminate spore contamination, a concentration of 80 ml/m3 is required over 24 hours. This method is suitable for heat-sensitive materials such as fur, synthetic fibers, and silk fabrics. Due to their poor penetration and high irritancy, disinfected items should be spread out, and the room must be kept sealed. (2) Glutaraldehyde Its effect is similar to that of formaldehyde. It is relatively stable in acidic solutions, but has poor bactericidal effects; it can remain stable in alkaline solutions for 2 weeks, yet the bactericidal effect is significantly enhanced. Therefore, typically 0.3% sodium bicarbonate is added to 2% valeraldehyde to adjust the pH value, thereby enhancing the bactericidal effect and allowing stability for 18 months. It is non-corrosive and possesses advantages such as broad-spectrum action, rapid efficacy, high heat generation, and low toxicity; it can be widely used for the disinfection of bacteria, spores, and viruses. It should not be used for disinfecting the skin and mucous membranes. (3) Ethylene oxide: It is a colorless liquid at low temperatures, with a boiling point of 10.8°C; therefore, it functions as a gaseous sterilant at room temperature. Its function is to disrupt the protein metabolism of microorganisms through alkylation. The typical application is 0.4–0.7 kg/m2 at 15°C for 12–48 hours. For every 10°C increase in temperature, the sterilizing power can more than double; a relative humidity of 30% yields the best sterilization results. It has advantages such as high activity, strong penetration, no damage to items, and no residual toxins, and can be used for disinfecting paper, books, cloth, fur, plastics, synthetic fibers, and metal products. Due to its strong penetrating power, it must be disinfected in a sealed container. Open flames must be avoided to prevent explosions. Ventilate after disinfection to prevent inhalation. 6. Others (1) Iodine Interferes with protein metabolism through halogenation. It acts quickly and durably, is non-toxic, and is minimally affected by organic substances. Sulfonated alcohols and sulfovuds (improper combinations of sulfonates and surfactants) are common. It is commonly used for the disinfection of skin and mucous membranes, as well as for emergency treatment of medical devices. (2) Chlorhexidine It is a biguanide compound. It has a strong disinfecting effect on bacteria. It can be used for disinfecting hands, skin, medical devices, clothing, etc., with a common concentration of 0.2–1‰.
Based on their effects on pathogen proteins, they are classified into the following categories. 1. Coagulating protein disinfectants include phenols, acids, and alcohols. (1) Phenols Mainly include phenol, lysol, hexachlorophene, etc. It has a distinctive odor, and its bactericidal effect is limited. It can cause textiles to change color and rubber products to become brittle; it also has a certain irritating effect on the skin. Therefore, apart from lysol, it is rarely used. Phenol (carbolic acid): a colorless crystal with a distinctive odor; it turns pink when exposed to moisture, but its disinfecting power remains unchanged. It is a protoplasmic poison for cells; at a concentration of 1:80 to 1:110, it can kill bacterial vegetative forms at 20°C within 30 minutes. However, it cannot kill spores or viruses with strong resistance. Adding soap can saponify fats, dissolve proteins, enhance penetration, and strengthen the disinfecting effect; however, it is highly toxic, irritating to the skin, and has an unpleasant odor, so it cannot be used for skin disinfection. Lysol (phenolic soap solution): It is made from 47.5% cresol and potassium soap. Red-brown in color, soluble in water, it has cleaning properties; its bactericidal power is 2 to 5 times greater than that of carbolic acid. It is commonly used as a 2–5% aqueous solution, and can be applied by spraying, wiping, soaking containers, and for hand washing. Bacterial vegetative forms can be killed within 10–15 minutes; however, its effectiveness against spores is poor. Hexachlorophane: It is a biphenol compound that is slightly soluble in water but readily soluble in alcohols, esters, and ethers; the addition of alkali or soap can enhance its solubility. It has low toxicity and irritation, but it possesses strong bactericidal properties. It is mainly used for skin disinfection. Washing hands with 2.5–3% hexachlorophene soap can reduce skin bacteria by 80–90%; however, there are reports of it causing nerve damage, so its long-term use is not recommended. (2) Acids They have a killing effect on both bacterial vegetative cells and spores. However, it can damage items, so it is generally not used for disinfecting living spaces. 5% hydrochloric acid can be used to disinfect tableware and fruits; adding 15% salt to a 2.5% solution can be used to disinfect fur and leather, by soaking them at 30°C for 40 hours per 10 liters of solution. Lactic acid is commonly used for air disinfection; fumigating a space of 100 m3 with 10 g of lactic acid for 30 minutes is sufficient to kill staphylococci and influenza viruses. (3) Alcohols: Ethanol (alcohol) – A 75% concentration can rapidly kill bacterial reproducing forms; it has a slower effect on ordinary viruses, its effect on hepatitis viruses is uncertain; it has a certain killing effect on fungal spores, but no effect on spores. Used for skin disinfection and soaking disinfection of thermometers. Since it cannot kill spores, it cannot be used for soaking and disinfecting surgical instruments. Isopropyl alcohol has a bactericidal efficacy of over 2. Protein-dissolving disinfectants are mainly alkaline substances, with sodium hydroxide and lime being commonly used. (1) Sodium hypochlorite: A white crystal that is highly soluble in water and possesses strong bactericidal properties. A 2–4% solution can kill viruses and bacterial forms, while a 10% solution can eliminate Mycobacterium tuberculosis. A 30% solution can destroy spores within 10 minutes. Due to its strong corrosive nature, it is used very rarely, only for eliminating anthrax spores. (2) Lime: When exposed to water, it generates high heat and dissolves proteins, thereby killing pathogens. A 10–20% lime milk solution is commonly used to disinfect excreta; the amount used should be twice that of the excreta. After mixing, it is left to act for 4–5 hours. 20% lime milk is used to disinfect areas contaminated with anthrax, applied every 4–6 hours for 2–3 consecutive times. Painting the walls twice can kill Mycobacterium tuberculosis spores. Due to its unstable nature, it should be prepared fresh at the time of use. 3. Oxidizing protein disinfectants Include chlorine-based disinfectants and peroxide-based disinfectants. Due to its strong disinfecting power, it is currently the most widely used in medical and epidemic prevention efforts. (1) Bleaching powder Most widely used. Its main component is calcium hypochlorite, with an active content of 25–30%. It is unstable and can be decomposed by light, heat, moisture, and CO2. Therefore, it should be stored in a sealed container in a dark and dry place for no more than 1 year. The active ingredient, hypochlorous acid, can penetrate into cells, oxidize the sulfhydryl groups of cellular enzymes, and disrupt cytoplasmic metabolism. It has strong and rapid bactericidal effects in acidic environments; at high concentrations, it can kill spores. In powder form, it is used for disinfecting feces, sputum, pus, etc. Add 200 grams of dry powder per liter, stir well, and let it sit for 1–2 hours. For urine, add 5 grams of dry powder per liter and let it sit for 10 minutes. The 10–20% emulsion, in addition to disinfecting excreta and secretions, can be used to spray toilets, contaminated vehicles, etc. If stored for a long time, the actual effective chlorine content should be measured to adjust the dosage used in preparation. The powder and tablets of bleaching powder contain 60–70% available chlorine; the amount used can be reduced proportionally. (2) Chloramine-T: It is an organic chlorine disinfectant containing 24–26% available chlorine; it is relatively stable, and when stored in a sealed container for 1 year, only 0.1% of its available chlorine is lost. Slightly soluble in water (12%), with low irritancy and corrosivity; its action is slower than that of hypochlorous acid. 0.2% can kill bacterial vegetative forms within 1 hour, 5% can kill Mycobacterium tuberculosis within 2 hours, while it takes more than 10 hours to eliminate spores. Various ammonium salts can enhance its bactericidal effect. 1–2.5% solutions are also effective against hepatitis viruses. The active liquid must be prepared 1–2 hours before use; if left for too long, its bactericidal effect is reduced. (3) Sodium dichloroisocyanurate, also known as Hypochlorite, is a widely used organic chlorine disinfectant with a chlorine content of 60–64.5%. It has advantages such as high efficiency, broad spectrum of activity, stability, high solubility, and low toxicity. Aqueous solutions can be used for spraying, soaking, or wiping; dry powder can also be used to disinfect contaminants directly, as well as to treat feces and other excreta, with a usage method similar to that of bleach. Spray directly on the ground at a rate of 10–20 g/m2. When mixed with polyformaldehyde powder and ignited, the gas can be used for fumigation disinfection. It can be mixed in a 1:4 ratio with coagulant No. 92 (synthesized from aluminum hydroxide chloride along with iron powder, sulfuric acid, hydrogen peroxide, etc.) to create \"Yu Shui Qing\", which is used for disinfecting drinking water. It can also be combined with sodium sulfonate to produce various disinfecting detergents, such as Dijingmei and Uochujing. It has a killing effect on hepatitis viruses. In addition, trisodium chlorophosphate and dibromocyanuric acid have similar effects. (4) Peracetic acid, also known as peroxyacetic acid, is a colorless and transparent liquid that is volatile and has an irritating acidic odor. It is a highly effective disinfectant that dissolves easily in water and organic solvents such as ethanol. It possesses bleaching and corrosive properties; its stability is low, as it decomposes easily when exposed to heat, organic substances, heavy metal ions, or strong bases. 0.01–0.5%; it can kill bacterial vegetative cells within 0.5–10 minutes, and spores can be killed at a concentration of 1% after 5 minutes. The commonly used concentration is 0.5–2%. Disinfection can be carried out by immersion, spraying, or wiping. Under sealed conditions, disinfection can also be achieved through aerosol application (at a concentration of 5%, 2.5 ml/m2) or fumigation (at a concentration of 0.75–1.0 g/m3). (5) Chlorine dioxide: A 3–6% solution can achieve disinfection in 10 minutes. 10–25% for 60 minutes; it can achieve sterilization and is used for disinfecting heat-sensitive plastic products, tableware, clothing, etc. 10% hydrogen peroxide gas deep-spray disinfection of contaminated surfaces in rooms ； 180–200 ml/m3; can kill bacterial vegetative cells within 30 minutes ； 400 ml/m3; spores can be killed in 60 minutes. Ethanol, when absorbed through the lungs, can cause **, but it causes no damage to the skin and can be used as a substitute for ethanol. (6) Potassium permanganate: Soaking at a concentration of 1–5% for 15 minutes can kill bacterial vegetative forms. It is commonly used for disinfecting tableware and fruits/vegetables. 4. Cationic surfactants Primarily quaternary ammonium salts; at high concentrations, they coagulate proteins, while at low concentrations, they inhibit bacterial metabolism. It has a bactericidal concentration, low toxicity and irritation, no bleaching or corrosive effects, is odorless, stable, and has good water solubility. However, its bactericidal power is weak, especially against spores; it is greatly affected by organic substances, and has many incompatible combinations, which are its disadvantages. In China, chlorhexidine, domiphen, and disinfectant are produced domestically; among them, domiphen has a strong bactericidal effect. The commonly used concentration is 0.5–1.0‰, and it can be used to disinfect skin, metal instruments, tableware, etc. It is not suitable for disinfecting excreta and secretions. 5. Alkylation disinfectants (1) Formalin It is a 34–40% solution of formaldehyde and possesses a strong bactericidal effect. A 1–3% solution can kill bacterial vegetative forms, while a 5% solution can eliminate spores within 90 minutes. For fumigation disinfection in indoor areas, a concentration of 20 ml/m3 mixed with an equal amount of water is typically used for 10 hours; to eliminate spore contamination, a concentration of 80 ml/m3 is required over 24 hours. This method is suitable for heat-sensitive materials such as fur, synthetic fibers, and silk fabrics. Due to their poor penetration and high irritancy, disinfected items should be spread out, and the room must be kept sealed. (2) Glutaraldehyde Its effect is similar to that of formaldehyde. It is relatively stable in acidic solutions, but has poor bactericidal effects; it can remain stable in alkaline solutions for 2 weeks, yet the bactericidal effect is significantly enhanced. Therefore, typically 0.3% sodium bicarbonate is added to 2% valeraldehyde to adjust the pH value, thereby enhancing the bactericidal effect and allowing stability for 18 months. It is non-corrosive and possesses advantages such as broad-spectrum action, rapid efficacy, high heat generation, and low toxicity; it can be widely used for the disinfection of bacteria, spores, and viruses. It should not be used for disinfecting the skin and mucous membranes. (3) Ethylene oxide: It is a colorless liquid at low temperatures, with a boiling point of 10.8°C; therefore, it functions as a gaseous sterilant at room temperature. Its function is to disrupt the protein metabolism of microorganisms through alkylation. The typical application is 0.4–0.7 kg/m2 at 15°C for 12–48 hours. For every 10°C increase in temperature, the sterilizing power can more than double; a relative humidity of 30% yields the best sterilization results. It has advantages such as high activity, strong penetration, no damage to items, and no residual toxins, and can be used for disinfecting paper, books, cloth, fur, plastics, synthetic fibers, and metal products. Due to its strong penetrating power, it must be disinfected in a sealed container. Open flames must be avoided to prevent explosions. Ventilate after disinfection to prevent inhalation. 6. Others (1) Iodine Interferes with protein metabolism through halogenation. It acts quickly and durably, is non-toxic, and is minimally affected by organic substances. Sulfonated alcohols and sulfovuds (improper combinations of sulfonates and surfactants) are common. It is commonly used for the disinfection of skin and mucous membranes, as well as for emergency treatment of medical devices. (2) Chlorhexidine It is a biguanide compound. It has a strong disinfecting effect on bacteria. It can be used for disinfecting hands, skin, medical devices, clothing, etc., with a common concentration of 0.2–1‰.