Ethanol concentration as bench antiseptic - (Dec/21/2008 )
According to various sources, 70% is the best concentration of Ethanol as a bench antiseptic. Supposedly, higher concentrations coagulate the outer proteins of many microorganisms but instead of killing them, send them into a latent stage.
1) Does anybody know if this has ever been tested, and if so, where (i.e. citation...)?
2) What do you use as a bench antiseptic in your lab? Is it different between molecular and live-specimens benches?
This paper contains some interesting citations:
We use cheap low grade ethanol diluted to approx. 70% in our in vitro laboratory without any problems.
Here are two old threads on this:
My understanding is that it's all about contact time -- 70% ethanol was arrived at as an antiseptic concentration because higher concentrations evaporate too quickly, thus reducing the contact time. This is why ethanol you buy in a pharmacy and ethanol prep pads used in medicine are also 70% ethanol.
Note: I didn't read tha papers linked to above, which may demonstrate my understanding to be utter nonsense....
well I have read the paper and it does not mention a mechanism of how a water-ethanol solution works. However it is interesting to note that a 66.5% Ethanol solution is effective at killing bacteria on skin. Maximum antimicrobial activity is between 50%-70% alcohol.
you can also try peroxide-based antiseptics (there are numerous products with different trade names). They are also effective against viruses and can be used in environments where use of ethanol is limited for fire safety reasons
Suggest you read Block's book - Disinfection, Sterilization, and Preservation. He hjs a chapter on alcohol and bug kill. Has nothing to do with evaporation.