Chemistry Reference
In-Depth Information
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Introduction to Gas
Chromatography
Gas chromatography is an analytical technique used to separate volatile
organic compounds. In the most generic form, chromatography is based on
the separation of compounds (or ions) present in a sample matrix. A whole
range of chromatographic techniques is available in the laboratory that, as well
as gas chromatography (GC), includes high-performance liquid chromatogra-
phy (HPLC), ion exchange chromatography (IEC), thin layer chromatography
(TLC), and size exclusion (or gel permeation) chromatography (SEC(GPC)).
Each type of chromatographic technique has its own area of application
based on the sample type, the analytes to be separated, the column technol-
ogy used to separate the analytes and type of detection system. Typically,
though, the sample must be in solution (either aqueous or organic) prior to its
introduction into the chromatograph. So a modern chromatographic system
is a sophisticated instrument that requires both technical expertise to use
and a combined practical and theoretical approach to utilize and maximize
its output fully.
Coupled inextricably with the chromatographic instrument is the inge-
nuity that has been applied to prepare samples (and their inherent matri-
ces) for analysis of their analytes. These procedures range from the simple
dilution aspect through concentration or cleanup approaches to chemical
modification of the analytes to make them amenable to the specific chro-
matography system. None of these systems, if they may be termed that, are
static. Developments take place on a regular basis in terms of different sam-
ple introduction/preparation, column technologies and detection systems;
sometimes they may be referred to as evolutionary and, occasionally, revo-
lutionary. All of this makes chromatography an exciting discipline both to
study and to use.
As already indicated, GC is responsible for the separation of volatile
organic compounds (VOCs). The first description of gas chromatography
was by James and Martin in 1952.
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Their instrument, by definition as the
first, was very different from what we see today in the analytical laboratory.
The instrumental developments and corporate imagery applied by the mod-
ern GC manufacturers (Table 1.1) that have taken place over the past 60 years
make the technique one of the cornerstones of the analytical laboratory. Of
course, without a detector, nothing can be detected after the GC separa-
tion. So the significant development of a range of detectors has been very
