Quaternary ammonium compounds

Detergents are organic molecules that serve as wetting agents and emulsifiers and are amphipathic in nature and hence solubilize otherwise insoluble residues and are very effective cleansing agents and are different from soaps, which are derived from fats.

Only cationic detergents are effective disinfectants characterized by positively charged quaternary nitrogen and a long hydrophobic aliphatic chain. They disrupt microbial membranes and may also denature proteins. Mostly used as disinfectants for food utensils and small instruments and as skin antiseptics. Several brands are on the market. Zephiran contains benzalkonium chloride and Ceepryn, cetylpyridinium chloride.

Aldehydes:

Formaldehyde and glutaraldehyde are highly reactive molecules that combine with nucleic acids and proteins and inactivate them, probably by cross-linking and alkylating molecules. Formaldehyde is usually dissolved in water or alcohol before use. A 2% buffered solution of glutaraldehyde is an effective disinfectant and is mostly used to disinfect hospital and laboratory equipments. These are mostly sporicidal and can be used as chemical sterilants.

Sterilizing gases:

Gases may also be used as sterilizing agents in order to sterilize many heat-sensitive items such as disposable Petri dishes and many syringes, heart-lung machine components, sutures etc. Ethylene oxide gas is used for this purpose as it readily penetrates packing materials, even plastic wraps and is both microbicidal and sporicidal and kills by combining with cell proteins. Batapropiolactone (BPL) is occasionally sued as a sterilizing gas inthe liquid form to sterilize vaccines and sera. Recently vapour-phase hydrogen peroxide has been used to decontaminate biological safety cabinets.