For establishing the correlation graph of OD260 vs HPLC peak area (Figure ), ODN 1a, which was synthesized at 1 µmol scale and purified with trityl-on RP HPLC, was dissolved in 1 mL water. Different volumes of the solution (see Table ) were injected into HPLC. For each injection, the peak area of the ODN was recorded, and the fractions corresponding to the peak were collected, combined and concentrated to dryness in a centrifuge evaporator under vacuum. The ODN was dissolved in 1 mL water. UV absorbance at 260 nm, which is the OD260 of the ODN in the corresponding HPLC peak, was obtained on a UV-Vis spectrometer using the solution in a 1 mL cuvette with a 1 cm light path, and on a NanoDrop Spectrometer using 2 µL of the solution (Table ). The correlation graphs of the values of OD260 vs the HPLC peak areas for the injections were generated and presented in Figure . The slopes of the lines obtained using OD260 measured using a UV-Vis spectrometer and a NanoDrop spectrometer are 0.00036 and 0.00038, respectively.