Ever wondered why cleaning products and hand sanitizers are mixed
at only 70% and not used at 99.9% isopropyl alcohol?
The presence of water in isopropyl alcohol is a crucial
factor in destroying or inhibiting the growth of pathogenic microorganisms.
Water act as a catalyst and plays a key role in denaturing
the proteins of vegetative cell membranes.
70% IPA solutions penetrate the cell wall more completely
which permeates the entire cell, coagulates all proteins and therefore the
microorganism dies.
Another plus side of having a higher water content is,
alcohol dries faster than water, therefore by having more water, this slows
down evaporation which therefore increases surface contact time allowing it to
be more efficient in destroying microorganisms.
Any mix below 60% isopropyl alcohol will not be effective
and when the mixture is above 90% the coagulation of the proteins is instant. This
then forms a protective layer which protects other proteins from coagulation effectively
making the product inefficient.
This means the leeway for cleaning products is between 60%
and 90% isopropyl alcohol with 10% to 40% purified water. 70% / 30% is the
preferred mix by medical professionals
SaFA Training & Consultancy Ltd run courses in
Bio-Hazard Awareness and through one of our partners, have delivered these to
Staffordshire Police Forensic Department
