How can I obtain DNA-free RNA using an RNeasy Midi or Maxi Kit?
FAQ ID -143

The RNeasy Midi/Maxi Handbook contains a protocol for the use of the RNase-Free DNase Set for on-column DNA digestion on RNeasy midi or maxi spin columns. Incubation times and reagent volumes have been modified from the standard RNeasy Mini procedure. See Appendix E of the RNeasy Midi/Maxi Handbook for the detailed protocol.