How do I quantify oligonucleotides by spectrophotometer?

Here is a protocol for the quantification of oligonucleotides by spectrophotometer:

  1. Add an aliquot of the resuspended oligonucleotide into a volume of PBS so that the total volume is 1000 µl. Typical dilutions are 1:20 or 1:40 where the dilution factor (DF) is 1000/aliquot volume.
  2. Vortex or pipette up and down repeatedly for 15 seconds.
  3. Read the absorbance of this dilution at 260 nm (OD260). Use the average of at least 2 reads.
  4. Calculate concentration using the nmol/OD260 value presented on the Certificate of Analysis, i.e. multiply (nmol/OD260) x (average OD260) x (Dilution Factor) = [C], concentration in µM (micromolarity).