High OD ratio from DNA Maxi Prep - (Jan/09/2008 )
After a maxi prep, I checked the OD.
3 pellets were resuspended in 300uL of EB each and the other 3 were resuspended in 300uL of sterile H2O. So each totals to ~900uL.
I used 5uL DNA in 95uL H2O.
EB= 260 reading of .781 and 280 reading of .305
H2O= 260 reading of .905 and 280 reading of .353
What would cause this high ratio? And is this good or bad?
you still have some contaminations.
it xould be interesting to have the OD230 value too.
At first, re pellet your DNA, do extensive 70%ethanolwash, dry efficiently the pellet (sensitive step) resuspend and recheck respective od.
if contamination still occurs, trat with proteinase K and RNAse A, and do a phenol chloroform extraction.