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reconstituted plasmid DNA solution slightly milky - (Nov/02/2006 )


i just used a Qiagen Maxiprep kit to purify and then precipitate (2.5 volumes of EtOH, 1/20th volume NaCl) plasmid DNA. dried centrifuged pellet and then reconstituted in 30 uL water. the resulting solution seemed slightly milky, and i was wondering what the possible cause for this was. Specced the solution, approximate yield was 2.5 ug/ul with an A260/280 ratio of about 1.55.

i don't know that the solution should be slightly milky. any ideas? thanks, folks smile.gif



ratio of 1.55 suggests some protein contamination. I would have guessed that it was due to concentration of your DNA, 30ul is a very small resuspension volume when using a maxiprep, but I think the problem lies in purity


what is the sensitivity of your spec? maybe as aimikins said you got that becaise its just too concentrated, try diluting it 1 in 10 and read again.


an alternative;

the DNA has been over dried. As a result it isn't going back into solution and is currently in the form of small insoluble particles