Quantitative assessment
Preferred measurement method: fluorescence-based methods like Qubit® (Invitrogen, Life Technologies), Quant-iT™ (Invitrogen) or Quantifluor (Promega).
We strongly discourage using Nanodrop for gDNA quantification.
HMW gDNA often requires extra homogenization effort (longer incubation time, increased incubation temperature, very extensive gentle mixing, etc.) to obtain accurate quantification. If separate DNA quantifications from the top and bottom of the sample are within 15% of each other, this is usually a good indication of adequate homogeneity.
If you have less than the requested amount of gDNA, we strongly recommend that you perform additional extractions to increase yield.
Qualitative assessment
Preferred measurement method: capillary electrophoresis-based methods like Fragment Analyzer or Bioanalyzer. High molecular weight DNA is greater than 15 kb in size and shows minimal smearing. Contamination, damage and degradation are revealed through a low molecular weight smear and should be removed using alternative cleanup strategies as described above.