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The chemical substances known as disinfectants are used to kill pathogenic organism.

Mechanism of Chemical Disinfectants

A chemical disinfectant acts by coagulating the bacterial protein or by changing the composition of protein so that is no longer exist in the same form

Commonly Used Disinfectants

  • Phenol
  • Lysol
  • Formalin
  • Dettol
  • Alcohol

The Choice of Disinfectant Based on

  • The strength of the solution
  • Type of bacteria to be killed
  • Type of articles
  • Length of exposure
  • The articles should be fully immersed in the lotions

Chemical Agent, Mechanism and Uses

  • Alcohols (ethanol, isopropanol)

Mechanism: denaturation of bacterial proteins

Uses: skin antiseptics, surface decontamination of incubators and cabinet interiors, disinfection of clinical thermometers

  • Aldehyde  (formaldehyde and glutaraldehyde)

Mechanism: inactivation of bacterial proteins

Uses: preservation of biological specimens, destroying anthrax spores in wool, fumigation.

Cold sterilant and fixative, surface decontamination, disinfection of hospital instruments, equipment, glasswares

  • Biguanides (chlorhexidine)

Mechanism: damage plasma membranes

Uses: skin and mucous membrane disinfection

  • Dyes (aniline dyes, malachite green, acridine dyes, acriflavine, proflavine)

Mechanism: react with acid group in cell

Impair DNA and destroy reproductive capacity

Uses: selective agents in culture media, e.g. LJ media

Skin antiseptic

  • Beta propiolactone

Mechanism: damage DNA, RNA and cause alkylation

Uses: fumigation, sterilization of biological products

  • Halogens (chlorine and iodine)

Mechanism: oxidizing agent and protein denaturation

Uses: surface decontamination, emergency spills clean-up, disinfectant

  • Metallic salts (silver, mercury)

Mechanism: combine with sulfhydryl groups, coagulate proteins and inactivate enzymes

Uses: antiseptic to prevent against gonorrheal infections in infants

  • Phenolic compounds (phenol, cresol)

Mechanism: damage to cell membranes, inactivation of proteins, oxidases and dehydrogenases

Uses: disinfectant in hospitals

  • Perioxides (hydrogen peroxide)

Mechanism: oxidizing agent

Uses: disinfectant

  • Quaternary ammonium compounds (zephiran, triclosan)

Mechanism: surface active agents (cationic detergent)

Uses: surface decontaminant and disinfecting equipment

  • Surfactants (soaps and detergent, sodium lauryl sulphate, benzalkonium chloride, cetrimide)

Mechanism: disruption of cell membrane

Uses: detergents and wetting agents


  • This method is used to sterilize instruments which are damaged by heat and metallic objects prone to corrosion
  • It is an easy method


  • A disinfectant cannot destroy the spores
  • Disinfectants are injurious to skin and the articles

General Instruction

  • The disinfectant chosen should destroy the pathogens
  • It should be used in correct strength
  • The article should be fully submerged it
  • The article should be kept in the disinfectant for sufficient time
  • The disinfectant should not be injurious to the skin and the article
  • The disinfectant should be cheap
  • Before dipping the article into the disinfectant clean it properly to free it from organic material
CHEMICAL DISINFECTANTS - Mechanism, Disinfectants, Chemicals uses & mechanism, Advantages, Disadvantages, General instruction
CHEMICAL DISINFECTANTS – Mechanism, Disinfectants, Chemicals uses & mechanism, Advantages, Disadvantages, General instruction


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