Agarose gel electrophoresis should be used to assess the intactness of high molecular weigh DNA.
Load approximately 10-20 ng of genomic DNA on to a minigel containing 1% agarose along with 50-100 ng of an appropriate molecular weight marker such as Lambda HindIII or Invitrogen 1 Kb Ladder. Run the gel for approximately 30 minutes minutes at 100V.
Intact genomic DNA can be viewed on this gel as a high molecular band with either minimal or absent lower molecular weight smear. The relative intensity of bands within the molecular weight ladder can be used to provide a qualitative estimate of the genomic DNA sample concentration based on relative fluorescent intensities.