Once the correlation graph is obtained, the OD260 for any ODN that has an HPLC profile, whether the profile is generated as a result of preparative or analytical HPLC, can be easily calculated. The ODN 1b, which was synthesized at a 0.2 µmol scale, is used as an example. One twentieth of the crude ODN was injected into HPLC. The area of the ODN peak was found to be 1690.6. Using the correlation line generated with the data from UV-Vis spectrometer in Figure , the area corresponds to an OD260 of 0.608. Alternatively, when the concentration of the ODN solutions are not very high, and the correlation is a straight line, the slope of the correlation line can be determined, and OD260 can be calculated from the slope. In present case, the slope is 0.00036, and the OD260 is 0.608 (1690.6 × 0.00036). With the number for a portion of the sample, the OD260 for the 0.2 µmol synthesis can be easily calculated, which is 12.16 (0.608 × 20). To validate the result, the OD260 of the synthesis was measured in a standard way using a UV-Vis spectrometer, and the value was 11.20, which was close to the value calculated from the graph or the slope. The method was further validated using ODN 1c using the same procedure for 1b, and the numbers from the graph and from standard measurement were 16.92 and 15.40, respectively. In both examples, the OD260 values from the standard measurements are slightly lower than those from the graph. This can be attributed to the inevitable loss of ODN during the collection of the samples from HPLC and subsequent material transfers before UV measurement.