Your blog suggested the use of 70% Isopropyl Alcohol for the disinfection of ultrasonic cleaners and work surfaces. Would a higher percentage of Isopropyl Alcohol (90%) work even better?
First, let me again clarify that I suggested the use of alcohol for disinfection, as opposed to a halogen (bleach) or a quaternary ammonium compound, because alcohol is not corrosive to stainless steel surfaces. Alcohols are effective at killing a wide range of micro-organisms (bacteria, fungi and mycobacteria) as well as inactivating viruses. They are not, however, effective against spores and some hydrophilic viruses.
Alcohols work by denaturing cellular proteins and dissolving some cellular lipids. Since proteins denature more quickly in the presence of water, and water is needed for alcohol to cross the cell wall, alcohols are most effective below 90% concentration. Above 90% concentration, alcohol will only dehydrate the cell wall without entering the cell and denaturing its proteins.
The two most common types of alcohol used in healthcare are ethyl and isopropyl. Since 70% isopropyl is less dehydrating to living tissue than 70% ethyl alcohol, 70% isopropyl is normally the choice for skin antiseptic and the most prevalently used. 70% isopropyl alcohol is also a common choice as both an antiseptic and disinfectant because of its relatively low cost (90% isopropyl cost more because of its higher alcohol content).
Always remember that in order for alcohol (or any other disinfectant) to be effective, the surface where it is being applied must be clean and dry (soil and moisture will inactivate disinfectants). Additionally, that surface should be saturated for the proper amount of time in order for disinfection to take place.
Finally, I also suggest that you download and print a copy of the CDC’s “Guideline for Disinfection and Sterilization in Healthcare Facilities 2008” (click this link). It is a great resource to have on hand and has a wealth of information on disinfectants and sterilants.