ddNTP solution
Dissolve each ddNTP (dideoxyribonucleoside triphosphates) in H2O at an approximate concentration of 100 mM. Use 0.05 M Tris base and a micropipette to adjust the pH of each of the solutions to 7.0 (use pH paper to check the pH). Dilute an aliquot of the neutralized ddNTP appropriately, and read the optical density at the wavelengths given in the table below. Calculate the actual concentration of each ddNTP. Dilute the solutions with H2O to a final concentration of 50 mM ddNTP. Store each separately at -70°C in small aliquots.
| Base | Wavelength (nm) | Extinction Coefficient (E)(M-1cm-1) |
| A | 259 | 1.54 x 104 |
| G | 253 | 1.37 x 104 |
| C | 271 | 9.10 x 103 |
| T | 267 | 9.60 x 103 |
For a cuvette with a path length of 1 cm, absorbance = Em.
