inactivating DNA/RNA with 70% ethanol - (Aug/08/2005 )
We all know what a sensitive procedure PCR is and how easy it is to get contamination despite all our precautions. In my lab, though we have separate areas for mixing our master mixes and adding template RNA, the hood in which I work does not have a UV light. The only means of contamination I can use are either a bleach solution or 70% ethanol. Does anyone know how efficient 70% ethanol is in sterilizing a workspace or pipettes of DNA/RNA?
Not very good, 70% ethanol, will precipitate the DNA/RNA a bit and still leave it in place. You could try using a dilute solution of NaOH (0.1M, pretty much what "RNAzap" is) to decontaminate the bench, I don't know what it would do the internal parts of pipettes, but it should be fine to treat the outside with them the same solution.
In addition to Bob's suggestion you can soak the pipettes in a (1%) bleach solution (I'm also not sure about NaOH on the inside of pipettes), then rinse them well with water (DEPC treated if working with RNA and are really paranoid), and let them dry completely (I use an oven at up to 80 C and leave them overnight).
I wouldn't use EtOH since it will precipitate the DNA if there is any there. It's OK for surface wipe-downs to get rid of bacteria (etc) but not for DNA.
you can also treat the plastic part y 5' sonication and bake metal parts at 80°.