DNA Quantification

From OpenWetWare
Revision as of 21:45, 29 January 2010 by Michael A. Speer (talk | contribs) (Procedure)
Jump to: navigation, search
back to protocols


This protocol uses a spectrophotometer to quantify the amount (μg/mL) of DNA and then uses a simple equation to convert this mass concentration into a molar concentration. The molar concentration is much more useful for most enzymatic processes.

  • Example: digesting 500ng of a 2KB plasmid is twice as much work as digesting 500ng of a 4KB plasmid with the same multiple cloning site.


  1. Dilute the DNA sample 30X by combining the following in a cuvette
  • 87µl water
  • 3µl DNA prep
  1. Run the DNA quantification (260/280) test on the spectrophotometer with a dilution of 30.
  2. Make sure that the A260 measurement is between 0.1 and 1.
  3. If is too low then repeat the measurement using 15X dilution.
  • 84µl water
  • 6µl DNA prep
  1. Calculate the molar concentration of DNA using the following equation.</br>
  • Picomoles/µl = DNA Concentration(µg/ml) / [0.66*DNA Size(bp)]