Why is the pQE DNA provided in QIAexpress Kits blue in color?
FAQ ID -487

The blue color results from bromophenol blue added to the plasmid DNA prior to lyophilization to make the DNA more easily visible. After the DNA pellet is resuspended in water or Tris-HCl, the dye will not inhibit downstream applications such as transformation of bacterial cells or restriction enzyme digestion.