Troubleshooting a Low 260/280 DNA ratio & Phenol storage - (Dec/28/2005 )

Hi,

I have got low (~1.3) 260/280 DNA ratios for two genomic DNA samples that I obtained using ethanol precipitation. A. What can cause this? B. What can I do to either remedy the situation or prevent it from happening again?

Also, does anyone know at what temperature liquid phenol should be stored at? I received a bottle from Fisher today and it was shipped with woodchips in the box- I was under the impression that phenol should be stored in the fridge for no more than 6 months....Is this false?

Thanks so much!!!

question #1 -
I would do an add'l p:c extraction, or whatever you use to remove proteins...

#2, I can't help you, I have always kept mine in the fridge (per instructions), but up to a couple years...someone here has said that phenol turns pink when it's croaking, due to pH changes, and that is how you know it's bad? but I have never had phenol that got that old

good luck!

Liquid phenol should be stored in the fridge. I throw it out (read: take it down to hazardous waste) when it turns yellow. By the time it is pinkish, it is really bad.

For your low 260/280 ratio, yeah, try and reextract it. If is is still low, run 100ng on a gel and see how it looks. If is looks good, it may be just fine depending on your application.