Page 42 - Illustrated Pocket Dictionary of Chromatography

COLUMN SWITCHING 37

column oven In most conventional GC systems the column is
housed in a sealed area, the oven, that is heated to produce the tem-
perature gradient. Note that part of the heating and cooling process
in a GC separation involves the heat transfer from the heating element
in the oven to the gas around the column and ultimately to the column
itself. Therefore, extremely rapid temperature increase rates are not
possible (e.g., a typical temperature gradient falls into the 1–20°C/min
range).
column splitter Used in gas chromatography to take the effluent
from one column and split it to two detectors. This enables the
analyst to achieve dual confirmation or increase the range of analytes
determined.

The column splitter is used on the end of a GC column in order to direct the efflu-
ent to two different detectors. This is used for dual confirmation analyses on a
single injection.

column switching Used to (1) prevent unwanted or column-
damaging components in the sample from reaching the separation
column or (2) generate trace enrichment of a component by concen-
trating the analyte band at the head of a column. The switching system
consists of two or more columns and one or more valve placed in
series. Flow is directed by switching the valves and redirecting the
flow stream.