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4.1.1 Column
The separation column, or column for short, of a gas chromatograph traditionally
consists of a relatively long spiral tube wound in a coil with a very small internal diameter.
The interior of this “column tube” is made of slow-reaction materials such as quartz glass
or stainless steel. These coating or filler materials are known as the “stationary phase”.
They are used as an adsorption layer for the gas molecules flowing through the column
and ensure the actual separation of the components. There are various types of
columns, see the figure below.
Typical dimensions of the used columns in the enCcal3000 have a length of several
meters and internal diameters of <0.1 mm. They are made of inert materials like fused
silica and stainless steel.
Figure 4.2: Different types of gas chromatographic columns
Various configurations exist:
•
Wall-coated open tubular column: the stationary phase is a thin liquid layer
coated on the inner wall of the column (for example type 5CB)
•
Packed capillary column: the stationary phase is coated on a packing, which is
equally distributed throughout the column (for example type HSA)
•
Support-coated open tubular column (SCOT column): the stationary phase is
a coated packing, which itself is coated on the inner wall of the column (for
example type M5S mole sieve)
•
Porous layer open tubular column: the stationary phase is a porous layer on
the inner wall of the column (for example type PPU)
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