Quantification

The delivered DNA oligonucleotide yield depends on several factors and may therefore vary considerably.

Concentration Measurement

The oligonucleotide concentration is determined by spectrophotometry as follows: An aliquot of the oligonucleotide solution is diluted 100-fold, and the absorption at 260 nm is measured and multiplied by 100 (A260).

Unit Definition

1 OD unit is the amount of oligonucleotide in 1 ml solution which exhibits an absorption value of 1 at 260 nm wavelength and 1 cm light path length. By taking into account the volume of water, in which the oligonucleotide is dissolved, the extinction coefficient and molecular weight of the oligonucleotide, the A260 value can be converted to OD units, concentration and yield. We use the following simple calculations:

Molecular Weight

The molecular weight of the oligonucleotide is estimated as the sum of the following constants minus 61.96 (MW(PO2 ÷ H)).

Concentration

The concentration (pmol/μl) is calculated as A260 divided by the extinction coefficient of the oligonucleotide. We estimate the extinction coefficient of the oligonucleotide as the sum of the contribution from the bases and use the following constants.

Yield

The yield in OD units is equal to: A260 x volume in μl / 1000 μl

  Molecular Weight Concentration
dA 313.21 0.0154
dG 329.21 0.0117
dC 289.18 0.0073
dT 304.2 0.0088
dI 314.19 0.0075
dN 308.95 0.0108
     

Modification extinction coefficients, will be added to the equation.

 

Information provided on the Vial Label

  • Oligonucleotide number
  • Oligonucleotide name
  • First 12 bases from 5' end
  • Lot number/Order ID
  • Concentration in pmol/μl
  • Shipping date
  • Number of bases