DNA quantitation - High OD values in alkaline lysis mini-preps. (Aug/16/2005 )
I have notice that when I perform plasmid DNA mini-preps using a Qiagen kit, I get a good relationship between OD260 and DNA concentration, as
measured by agarose gel electrophoresis. However, when I purify plasmid
DNA using alkaline lysis protocol with homemade reagents, I get an overstimation of DNA concentration by OD260 measurement.
you probably get some RNA contamination. btw, you can heat at 50° for 5' before measurment for more accuracy.
You probably got lots of contamination using this method - happens in my experience, I would always use kit if need good sequence.