70% ethanol in tap water... - (Apr/14/2012 )

I do not want dead bacteria in my safety cabinet or anywhere. My lab does not have a DI water outlet. I'm planning to buy this http://www.fishersci.com/ecomm/servlet/fsproductdetail?storeId=10652&productId=3786902&catalogId=29104&matchedCatNo=ZFDI%20000%2001&fromSearch=1&searchKey=aqua||h20||waters||DI||water&highlightProductsItemsFlag=Y&endecaSearchQuery=%23store%3DScientific%23nav%3D0%23rpp%3D15%23offSet%3D0%23keyWord%3DDI%2Bwater&xrefPartType=From&savings=0.0&xrefEvent=1334428848910_0
and set up in my lab. But Is mixing 200 Proof Absolute Alcohol to DI water by 70% absolutely fail-proof? They say DI water 'has' bacteria in it. Or is it best to keep buying 70% reagent alcohol?
Thanks

It may be equally economical for you to use medical-grade sterile water eg. water for injection or water for irrigation.

You don't need to use absolute ethanol. I was perfectly fine using low grade denatured ethanol (one denatured with methanol, acetone, or isopropanol - which actually makes it stronger disinfectant).

Also you could comparing cost to commercially available disinfectants like "Klericide" etc.

I'm from USA. I don't think Klercide is available here. Will, using disinfectant wipes do the work http://www.fishersci.com/ecomm/servlet/fsproductdetail?storeId=10652&productId=744804&catalogId=29104&matchedCatNo=0435587&fromSearch=1&searchKey=disinfectants||disinfectant&highlightProductsItemsFlag=Y&endecaSearchQuery=%23store%3DScientific%23nav%3D0%23rpp%3D15%23offSet%3D0%23keyWord%3Ddisinfectant&xrefPartType=From&savings=0.0&xrefEvent=1334433018209_3 ? So I don't have to spray everything with ethanol inside the hood.

I'm just starting off with cell culture and there was a contamination in my first run. I'm too skeptical after that, that I keep spraying a lot of ethanol over and over again, so that it gets over soon!

cshmech on Sat Apr 14 19:54:00 2012 said:

I reread the OP and sorry I finally realised what you were asking...but spraying with 70% ethanol in whatever kind of water won't exactly solve your problems of contamination......it can be due to a lot of other factors or from other sources ( and a combination thereof) and not necessarily from a contaminated hood...

I found out where the contamination was from. It was from mishandling in the water bath. But I became skeptical after that!

K.B. on Sat Apr 14 11:13:14 2012 said:

Not sure what you mean here... because there is no microiological reason to prefer dH20 in stead of using tap water...
Same goes for ddH20.

Trof on Sat Apr 14 15:14:55 2012 said:

You are using MQ water to make 70% ethanol? Either you are not cleaning a lot with that or your lab must be filthy rich..
I also wonder: how often is your MQ system checked? Because often labs buy this kind of equipment, but dont really check it like they should.

Okay, If i install a DI water source is it gonna make any difference or will it be the same as using the tap water? And what is an MQ system?

cshmech on Fri Apr 20 18:52:57 2012 said:

The DI water, you mean distilled water or demineralised?

There is no reason , microbiologically, to use "special" water for the ethanol solutions.
So not sure its worth making the trouble.
It all depends on what you expect.
The major reason to use "special" water is to lower the lime content in the water to prevent getting lime spots on glasware or clotting of spraybottles etc.

MQ = milli Q water (http://en.wikipedia.org/wiki/Milli-Q)

DI - de-ionized water.

cshmech on Fri Apr 20 23:40:23 2012 said:

Its just another word for demineralized water