phenol extraction problem - (Jun/16/2006 )

Hi all,

I followed the standard phenol/chloroform extraction to purify DNA, and found a big chuck of pellet at the bottom of the tube after NaAc and 100% ethanol precipitation. The big chuck still exists after 70% ethanol washing. This white chuck can disolve very fast in water. When I check the DNA concentration using spec. The DNA conc. is 70ng/ul, 260/280 is 1.67, 260/230 is 1.45. I am not sure what is that white pellet. What is the amount of DNA that you are able to visualize with naked eyes?

Thanks,

Hi Rena,

For plasmid extraction, if you are extracting from a few mLs of bacterial culture, you can expect a few mg of DNA. If so, the pellet should not be too big and it should be just visible.

Regards,

Charles

i've replied to you mail, but would add to charle's answer that plasmid DNA from few ml culture should e few µg?...

Thanks a lot. Do anybody know if SDS and EDTA can be removed after phenol/chloroform extraction?

for EDTA, i'm quite sure it's removed when washing by EtOH 70%. .SDS probably too but i'm not sure

Hi Fred,

Yes, you are right. The yield of plasmid should be a few ug. I typically get 100ul at a concentration of 70ug/ul from 1.5ml of culture.

Thanks for that,

Charles