The number of nanomoles of an oligonucleotide is calculated from the measured A260 value using the millimolar extinction coefficient (mM E260) of the specific oligonucleotide.
Nanomoles = 1000(Measured A260 value x dilution factor x total volume)/ (E260 of bases + E260 of modifiers)
The mM E260 values MIDLAND uses are:
A = 15.1 | G = 11.7 | T = 8.7 | C = 7.4 | I = 6.8
For example, a 2.0 milliliter sample with the sequence 5′-ATC GAT CGG ATT-3′ has a measured A260 value of 0.329 when measured at a 1:11 dilution. The total number of nanomoles in the sample is calculated as follows:
Nanomoles = 1000 x 0.329 x 11 x 2.0 / 3(15.1) + 3(11.7) + 4(8.7) + 2(7.4) = 55.7 nanomoles