STERILIZATION AND ITS CHEMICAL METHODS.

In last post we discussed about sterilization and its physical methods. In this post we will discuss about sterilization and its chemical methods in the most precise way.

By this far we know that sterilization can be defined as the process of killing all microorganisms (including spores) on or in a material or object. We also know that heating is the most common and reliable method for sterilization. 

Here are some chemical methods of sterilization:

1) Gases:

Types used in sterilization:
a) Ethylene oxide
b) Formaldehyde gas: This is widely employed for fumigation of OT and other rooms.
c) Betapropiolactone: 
-having rapid bactericidal activity but carcinogenic.
- capable of killing all microorganisms and is very active against viruses.

2) Surface active agents: 

Substances that alter the energy relationship at interfaces, producing a reduction Of surface or interfacial tension is called surface active agents.

They are widely used as wetting agents, emulsifiers and detergents. These are in four main groups:
a) Anionic
b) Cationic 
c) Non ionic
d) Amphorteric.

3) Metallic salts:
 
Though all salts have a certain amount of  germicidal action depending on their concentration. Salts of heavy metals have a greater action. 
Eg: salts of silver, copper and mercury. 

They are protein coagulants and have capacity to combine with sulfhydrill group of cell enzymes. 

4) Alcohol:
Frequently used are ethyl alcohol, isopropyl alcohol. These must be used at the concentration of 60-90 %

5) Aldehyde:
Formaldehyde- Having bactericidal, sporicidal and has lethal effect on viruses. 
Used to preserve anatomical specimen. 

6) Glutaldehyde:
Effective against tubercile bacilli, fungi, viruses.
Less toxic and irritant to eyes and skin.

7) Dyes: 
Aniline dye and acridine dye.
Both are bacteriostatic in high duration but are of low  bactericidal activity.
Aniline dye is more active against gram +ve than gram -ve organisms.

8) Halogens:
Iodine having active bactericidal activity and moderate action on spores.

9) Chlorine:

Used to disinfect water supplies, swimming pool and food and dairy industries. Also acts on viruses.

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