Page 30 - Multidimensional Chromatography
P. 30
20 Multidimensional Chromatography
the main column. Cold trapping occurs when the solutes reach an analytical column
which is maintained at a temperature too low for them to migrate, so they accumu-
late and concentrate until the oven temperature is increased sufficiently to allow
them to move through the column.
Figure 2.2 Schematic representation of an on-column interface. The eluent leaving the
HPLC detector enters the valve and in the stand-by position, leaves it to go to waste. When the
valve is switched on, the eluent is pumped through the transfer line into the inlet of the on-
column injector. The liquid floods the capillary wall, thus creating a layer that will retain the
solutes. Evaporation occurs from the rear part of the solvent so refocusing the chromato-
graphic band. At the end of the transfer, the valve is switched off, and the eluent again flows to
waste.
