is there switch valves available which you can place between online purification column and an analytical column? You could then have this directed to waste e.g during 0-3 min and to analytical column after 3 min within an injection? Can you get this valve controlled by standard software? Please give references, where can I find this. Many thanks.

Click on the "Rheodyne" link near the upper left of the Forum. They are probably the largest manufacturer of HPLC switching valves and injectors.