Genomic DNA quantification using the NanoDrop - (Sep/25/2014 )

I read that genomic DNA quantification using the NanoDrop may be inaccurate due to the lengths of DNA strands but I used a genomic DNA purification kit which renders the DNA into fragments no larger than 100 KB. Is this too long for accurate NanoDrop readings?

There should be no problem with fragments that size.

Out of curiosity, at what size does this become an issue? I mostly use our nanodrop for quantification so it would be good for me to know :-)

With DNA that is of the megabase or greater size, the strands physically clump together, which is why you can spool them with a glass rod. Although they are dissolved, the solution is not uniform in concentration, so pipetting it is problematic, especially for small volumes. Shearing the DNA, or using columns shortens the strands and makes the solution more  uniform in density. I'd say 100 kb is about the point at which this is a major factor, but if you told me it was several fold larger or smaller, I would not be shocked.