This plumbing scheme allows slower eluting components (end cut) which are not of interest to be backflushed to vent. Often a shorter version of the analytical column is used as the precolumn.
Once all components of interest have entered the main column (at port 2), the valve is switched, backflushing the precolumn to vent and reducing analysis time. An auxiliary source of carrier or mobile phase is required for this application
Click below to change the valve position. (Currently shown in Position A)
A: Slower-eluting compounds collected in precolumn
B: Contents of precolumn backflushed to vent
