Capillary Chromatography - Apparatus for use with Capillary Columns - Gas Supply
Apparatus for use with Capillary Columns
The apparatus used specifically with capillary columns differs very little from the general gas chromatograph. Capillary columns require particular sampling systems and also have a more restricted range of suitable detectors than those usable with packed columns, but other than that, the capillary gas chromatograph is identical to that used with packed columns. A diagram of the lay out of a gas chromatograph used specifically with capillary columns is shown in figure 5.
The gas supply incudes the usual gas tank, reducing valve and flow controller; the pressures and flow rates are typically computer controlled. The carrier gas is usually nitrogen, argon or helium, helium being the most commonly used (at least in the USA). If the detector is a flame ionization detector (FID), the gas supply will include hydrogen and air or oxygen together with appropriate reducing valves and flow controllers. The gas lines should contain the usual filters to ensure any debris is not passed into the columns.
Figure 5. The Basic Capillary Column Gas Chromatograph