The common and most widely using disinfectant in the pharmaceutical industries, hospitals and other health care facilities is 70% isopropyl alcohol( or ethyl alcohol in the case of sanitizers). It is used for disinfection of hands and equipment surface and surgical devices.
The important thing is that only
70% solution of isopropyl alcohol acts as a disinfectant killing all surface
microorganisms. 70 % isopropyl alcohol solution kills microorganisms by
dissolving the plasma membrane of the cell wall. Plasma membrane of gram
negative bacteria consist of thin layer of peptidoglycan that easily destroyed
by the alcohol.
Water plays key important role
which used to denature the proteins of cell membrane and acts as a catalyst in
the reaction. Contact time of the alcohol with the organism also play an
important role. A 70% solution of alcohol takes more time in evaporation from the
surface, increasing the contact time. Therefore, 70% isopropyl alcohol fulfills
the both requirements.
The 100% isopropyl alcohol
coagulates the proteins instantly by creating a protein layer that protects the
other proteins from further coagulation. Due to this microbes are not killed
but remains in dormant stage. While 70% isopropyl alcohol solution penetrates
in the cell wall at slower rate and coagulates the all protein of the cell wall
and microorganism dies.
Ref: (Staphylococcus aureus
killed in less than 10 seconds with a 50% Isopropyl Alcohol solution and was
not killed in 2 hours with a 90% solution: emphasizing the importance of water
in killing microorganisms (Tainter et al., 1944)
Thus 70% alcohol solution in
water is more effective then 100% absolute alcohol and have more disinfectant
capacity. Hence 70 percent iso propyl alcohol is known as pharmaceutical
alcohol.
“These alcohols are rapidly
bactericidal rather than bacteriostatic against vegetative forms of bacteria;
they also are tuberculocidal, fungicidal, and virucidal but do not destroy
bacterial spores. Their cidal activity drops sharply when diluted below 50%
concentration, and the optimum bactericidal concentration is 60%–90% solutions
in water (volume/volume)”.
Addition of water (due to high
dielectric constant) to alcohol breaks the hydrogen bonds (due to hydrogen
bond, alcohol molecules are inactive) between the alcohol molecules and make
molecules active. There is a critical concentration of water molecules which
makes maximum free alcohol molecules. 30% water concentration is critical
concentration for isopropyl alcohol therefore, 70% isopropyl alcohol is used as
disinfectant (Dr.Nishod Saxena)
Staphylococcus aureus killed in 1
minute; Escherichia coli killed in 5 minutes
Now i know your sanitizer probably used between 60 -70% ethyl alcohol. Relax, its also SAFE. But never go below 60 or above 90.
Shalom.
Shalom.
Source - linkedin
Mohamed Anvar Deen. A.L.,
Strides Shasun Pharmaceuticals
Limited.
Feel free to leave a comment after you read, ill respond in my spare time and incorporate changes in coming articles. thanks. DAMI
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