Q1:How soon will a sample be eluted after starting a sample run and how much solvent will be used?
A1:The eluting time and the amount of solvent to be used can be predicted pretty accurately, when a sample is correctly run on TLC and get the Rf value of the target compound. The eluting position is given by the formula of CV (Column Volume) = 1/Rf. If the target compound reads Rf 0.25 on the TLC, it will be eluted at 4-CV position as shown in Fig.1. And the amount of solvent used is 4-CV. (Note: CV means the void volume in a column. 1-CV is the amount of solvent required to fill up the void volume. Non-absorbing matter will elute at 1-CV.). Then, the eluting time is given by 4-CV/Flow Rate. The eluting time of the open-column chromatography and that of the flash chromatography differ as shown in Fig.2. Gradient method on flash chromatography increases the sample resolution as shown in Fig.3.

go to top