DNA absorbance readings

calliphora at cityweb.de calliphora at cityweb.de
Mon Dec 3 14:01:24 EST 2001

On Tue, 27 Nov 2001 15:16:51 -0500, Tina Higgins <thiggins at wpi.edu>

>(High A260/A280 in DNA-readings after Phenol/Chloroform-Extraction)

If you don´t remove Phenol carefully after
Phenol/Chloroforn-extraction, traces of Phenol in Your sample give a
strong absorption at 260nm - but not at 280nm. This results in the
reported high A260/A280-ratio. In this case You mainly measure the
concentration of Phenol in the sample, but not DNA, so that the common
method to estimate the DNA-concentration multiplication of the A260
with 50 will result in a high overestimation of the DNA-concentration.
Ernst Kiehl
Institut für Zoologie II
Universität Düseldorf

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