Page 26 - Tandem Techniques

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increasing distribution coefficients with respect to the stationary phase; ipso facto a separation is
achieved. The mobile phase can be a gas or a liquid which gives rise to the two basic forms of
chromatography, namely, gas chromatography (GC) and liquid chromatography (LC). The stationary
phase can also take two forms, solid and liquid, which provides two subgroups of GC and LC, namely;
gas-solid chromatography (GSC) and gas-liquid chromatography (GLC), together with liquid solid
chromatography (LSC) and liquid chromatography (LLC). The different forms of chromatography are
summarized in Table 1.
Table 1.1 Different Forms of Chromatography
MOBILE PHASE STATIONARY PHASE
GAS LIQUID
Gas-Liquid Chromatography
Gas Chromatography (GLC)

(GC) SOLID
Gas-Solid Chromatography
(GSC)
LIQUID LIQUID
Liquid-Liquid Chromatography
Liquid Chromatography (LLC)

(LC) SOLID
Liquid-Solid Chromatography
(LSC)

It should be pointed out that the above classification is fundamental and all chromatographic
separations will fit into one of the four classes. For sundry reasons, various other terms have been
introduced by analysts in the field to describe certain subgroups of chromatography. Thin-layer
chromatography (TLC) has been introduced to describe certain forms of lamina chromatography
systems, size exclusion chromatography (SEC) for separations based on molecular size, reversed-phase
chromatography (RPC) for chromatographic separations that are determined largely by dispersive
interactions with the stationary phase, and there are many more. These terms can be confusing to those
unfamiliar with the technique but,