What are Disinfectants, Definition, Classification, Examples, Advantages: 

Disinfectants Definition :

• A disinfectant is a chemical substance or compound used to remove or kill microorganisms on inert surfaces.

• Chemical disinfectants are chemical substances that are used to remove or kill pathogenic and non-pathogenic microorganisms from the inert surface.

• Disinfectants are any chemical substances that can be used to kill or remove microorganisms, such as bacteria, viruses, and fungi by chemically degrading their building blocks or disrupting their metabolism.

What is a Disinfectant?

• Disinfectants are mainly used in various places and required disinfection work to kill bacteria, fungi, viruses, and other microorganisms.

• According to different places of use, disinfectants can be divided into household disinfectant, industrial-grade disinfectant, food-grade disinfectant, etc.

• Based on Chemical ingredients disinfectants are different types such as Sodium hypochlorite, quaternary ammonium salt, chloro-meta-xylenol (Dettol disinfectant, Willows disinfectant ), peracetic acid, etc.

• The ideal disinfectant should have a wide bactericidal spectrum, strong bactericidal ability, fast action speed, good stability, low toxicity, corrosiveness, and low irritation (should be non-toxic, non-residue, non-corrosive, non-irritating), easily soluble Water, safe for humans and animals, cheap and easy to obtain, and low pollution to the environment.

• Examples of Chemical Disinfectants such as Alcohol, Chlorine, and chlorine compounds, Formaldehyde, Glutaraldehyde, Hydrogen peroxide, Iodophors, Ortho-phthalaldehyde (OPA), Peracetic acid, etc.

Classification of Disinfectants : 

Disinfectants can be divided into three categories according to their ability to sterilize microorganisms　

(a) High-efficiency disinfectant refers to a disinfectant that can kill all microorganisms, including bacteria, fungi, spores, and viruses. Such disinfectants are also called sterilants. There are chlorine dioxide, hydrogen peroxide, glutaraldehyde, etc.

(b) Moderate disinfectant: refers to disinfectants that cannot kill bacterial spores but can kill bacterial propagules, fungi, and most viruses. There are ethanol, chlorine preparations, and so on. 

(c) Inefficient disinfectant: refers to the disinfectant that can kill most bacterial propagules, some fungi, and viruses, but cannot kill bacterial spores, Mycobacterium tuberculosis, and some fungi and viruses. There are chlorhexidine, Xinjieermin peracetic acid, sodium hypochlorite, and so on.

Example of Disinfectants: 　　

Below we are given common types of chemical disinfection and their mechanism of action and characteristics

1. Peroxides Disinfectants: 

• The sterilization mechanism is to release new ecological atomic oxygen and oxidize the active groups in the bacteria. 
• The sterilization feature is fast and strong and can kill all microorganisms. Including hydrogen peroxide, ozone, chlorine dioxide, etc. 
• This type of disinfectant is a sterilant. Widely used in medical disinfection and industrial sterilization.
• Hydrogen peroxide is a colorless liquid commonly used as a bleach and disinfectant.
• Hydrogen peroxide is available at 3-6% concentration for home and simple first aid over-the-counter use, 30% for laboratory use, and 68% for industrial production.
• It is suitable for disinfection of object surfaces, indoor air, skin wounds, and corrosion-resistant medical devices.
• Hydrogen peroxide is used as a basic disinfectant in very low concentrations, which favors the chemical’s degradation to simple water and oxygen
• Hydrogen peroxide is also used in odor removal in wastewater treatment, peroxide is used in rocket propellants, and the production of sodium percarbonate and sodium perborate.
• The biggest disadvantage of  Liquid peroxide disinfectants are corrosive, irritating to eyes, mucous membranes, and skin, and have the risk of burns.  
• It is flammable and explosive. It will cause combustion and explosion in case of open flame and high heat. In contact with reducing agents, there is a danger of combustion and explosion in the case of metal powder.

2. Halogen Disinfectants: 

• It is the most widely used and most diverse type of disinfectant. The main ones are chlorine and iodine.
• The sterilization mechanism is to oxidize the active groups in the bacteria and combine them with amino groups to denature proteins. 
• Halogen sterilization can kill most microorganisms.
• The sterilization process is greatly affected by environmental conditions.
• Halogens disinfectant: bleaching powder ( Sodium hypochlorite), chloroquine, trichloroisocyanurate (sodium), iodophor, etc. 
• This type of disinfectant is a medium-efficiency disinfectant. 
• Among them, chlorine-containing preparations are mainly used in industrial disinfection.
• Bleaching powder is the best example of halogen disinfectants. 
• It is made of chlorine mixed with slaked lime. It is a mixture of calcium hypochlorite, calcium chloride, and calcium hydroxide.
• According to the requirements of sanitation and disinfection standards, bleaching powder with effective chlorine less than 15% is not allowed to be used for disinfection.

3. Phenol disinfectants: 

• The sterilization mechanism is protein denaturation, precipitation, or inactivation of the enzyme system; phenols can inhibit and kill some bacterial propagules and lipophilic viruses. 
• Examples of phenol disinfectants should are Lysol water (cresol), phenol, etc. 
• The commonly used cresol soap is also known as Lysol, and its main component is cresol. 
• Halogenated phenol can enhance the bactericidal effect of phenol. For example, trichlorodiphenyl ether has been widely used as a preservative for clinical disinfection and antiseptic.
• This type of disinfectant is a low-efficiency disinfectant. 
• The agent has been widely used in clinical disinfection and antiseptic.
• Mainly used for medical disinfection.

4. Aldehydes Disinfectants: 

• The principle of this type of disinfection is that an active alkylating agent acts on the amino group, carboxyl group, hydroxyl group, and sulfhydryl group in the microbial protein, thereby destroying the protein molecule and causing the microorganism to die.
• It is effective on bacteria, spores, fungi, and viruses. 
• Formaldehyde, glutaraldehyde is examples of aldehyde disinfectants.
• Can be used as a sterilant. 
• Aldehydes can kill all kinds of microorganisms. Because they have stimulating and curing effects on human skin and mucous membranes and can sensitize people.
• They cannot be used for disinfection of air and tableware and disinfection in the field of food. 
• Generally, they are only used for the disinfection of surface and space disinfection of medical and sanitary equipment.
• The cost is high, mainly used for the disinfection of instruments.

5. Quaternary ammonium salt cationic surfactant: 

• The sterilization mechanism is to change the permeability of the cell membrane, make the cytoplasm leak out, hinder respiration or protein denaturation. 
• The characteristic is that it can kill bacterial propagules, but has a poor effect on spores, fungi, viruses, and Mycobacterium tuberculosis. 
• Quaternary ammonium salt disinfectants are a category of disinfectants, such as Jieerfen (benzalkonium chloride), new Jieerfen (benzalkonium bromide), dumbphone (dodecyldimethylphenoxyethyl bromide), ammonium, and some compound quaternary ammonium salt disinfectants.
• It is a medium-effective disinfectant.
• Generally suitable for disinfection of skin, mucous membranes, surgical instruments, and contaminated work clothes.
• Newly developed double-chain quaternary ammonium salt disinfectants have a better bactericidal effect than single long-chain quaternary ammonium salts.

6. Alcohol Disinfectants: 

• The sterilization mechanism is to denature proteins and dry up metabolism. 
• The bactericidal characteristics make it effective against bacteria and ineffective against spores, fungi, and viruses.
• This type of disinfectant is a medium-efficiency disinfectant. 
• Alcohol disinfectants the most commonly used are for hand skin disinfection and medical instruments disinfection. 
• Examples of alcohol disinfectants are ethanol and isopropanol.
• The usual concentration is 75% but according to various reports: 80% ethanol has a good inactivation effect on the virus.
• Mainly used in food processing, medical and health tools, instruments, surface disinfection of hands.

7. iodine-containing disinfectant: 

•  Iodine tincture and iodophor are commonly used iodine-containing disinfectants and they can kill bacterial propagules, fungi, and some viruses.
• Iodine is an essential nutrient and has been generally used as an antiseptic for skin wounds, as a disinfecting agent in hospitals and laboratories, and in pharmaceuticals
• One of the most widely used iodophors is povidone-iodine, which is often used for the disinfection of surfaces in breweries and dairy industries. 
• Iodophors are generally less toxic than other disinfectants, but they leave a yellow residue on surfaces.
• Iodine-containing disinfectant can be used for skin and mucous membrane disinfection and is often used in surgical handwashing in hospitals.

8. Other disinfectants: Commonly used gas disinfectants such as ethylene oxide and mildew have a killing effect on bacterial spores, fungi, rickettsia, viruses, molds, etc. It has the characteristics of strong penetration, easy diffusion, fast elimination, no damage to items, and corrosion. Due to its strong penetrating power, it is often used for disinfection or sterilization after packaging leather, plastic, medical equipment, and medical supplies, and it is also suitable for most objects.

Precautions when using disinfectants :

• Most of the disinfectants are flammable. It should be stored in a cool, dry, and ventilated place away from light. Should be placed out of the reach of children.

• The room should be disinfected by wiping. Alcohol should not be sprayed on the body.

• Disinfectants for external use should not be taken orally. Use caution in people allergic to alcohol.

• If ethanol is used alone for hand disinfection, it is recommended to use hand cream after disinfection.

• When the sterilized items are seriously polluted by organic substances, the concentration of use should be appropriately increased or the action time should be prolonged, or two disinfection should be performed.

• Wear a mask and gloves when preparing and repacking the disinfectant; wear gloves when using it to avoid contact with the skin. If accidentally splashed into the eyes, rinse immediately with water, and seek medical attention in severe cases.

• Serious burns to the cornea, skin, and mucous membranes may be caused at high concentrations, and personal protection should be taken during operation. In case of contact, rinse immediately with plenty of water and seek medical attention in time.

• After disinfection of tableware and medical equipment, the residual disinfectant should be washed with clean water in time before it can be used on the human body

• Disinfectants used in dentistry must be wide bactericidal spectrum; low effective concentration; fast action speed; stable nature; easily soluble in water; can be used at low temperature; Influence; non-corrosive to articles; colorless, tasteless, odorless, easy to remove residual drugs after disinfection.

• Disinfectants used in salons must be EPA registered, low toxicity, not easy to burn and explode, non-hazardous to use; low price; easy to transport, can be supplied in large quantities.

• Disinfectants used in licensed establishments must be bactericidal, virucidal, fungicidal, and pseudomonacidal and they must be effective against HIV-1 and Human Hepatitis B Virus or Tuberculocidal.

Advantages of Disinfectants: