IUBio Biosequences .. Software .. Molbio soft .. Network News .. FTP

Measuring DNA Concentration: UV absorption shift?

Yvonne Thorstenson yvonne at SEQUENCE.STANFORD.EDU
Tue Feb 4 18:52:31 EST 1997


In trying to improve measurement of DNA concentration, I obtained a
spectrum of UV absorbance by scanning from 200 to 325 nm.  In five
samples, there was only a very weak absorbance at 253 nm, and a stronger
absorbance at 217 nm.  The absorbance at 253 nm is too weak to account
for the amount of DNA I see on an agarose gel, but the absorbance at 217
nm is about right.

  I suspect that the DNA samples are contaminated with something.  They
were purified from agarose using two different gel extraction methods. 
What would cause the absorbance of a DNA sample to shift from the
expected maximum at 260 nm to 253 nm, or even 217 nm?

Yvonne Thorstenson



More information about the Methods mailing list

Send comments to us at biosci-help [At] net.bio.net