DNA Quantification

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Revision as of 00:43, 30 January 2010 by Michael A. Speer (Talk | contribs)
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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)]



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