Agriculture Reference
In-Depth Information
Table 9.1. Fundamental Types of Chromatography
Types of
Compounds
Type of
Stationary
Amenable
Chromatography
Phase
Mobile Phase
to Separation
Gas (also GLC
a
High-boiling
Gas
Compounds to be
and GSC
b
)
liquid
separated must
be in gaseous
phase
HPLC
c
Solid
Solvent, aqueous,
Compounds or ions
aqueous solution;
must be soluble in
solvant, or mixture
mobile phase and
of solvants
have appreciable
attraction to
solid phase
TLC
d
Solid
Solvent, aqueous,
Compounds or ions
aqueous solution;
must be soluble in
solvant, or mixture
mobile phase and
of solvants
have appreciable
attraction to
solid phase
Electrophoresis
Solid or
Curerent
Compounds or ions
semisolid in
must be ionized
a buffer
to be separated
solution
a
Gas-liquid chromatography.
b
Gas-solid chromatography.
c
High-performance liquid chromatography.
d
Thin-layer chromatography.
9.2.2.
Mobile Phases
In gas chromatography common mobile phases are hydrogen, argon, helium,
and nitrogen gases and air; helium and nitrogen are the most commonly used.
Because gas chromatographic detectors are extremely sensitive and it is desir-
able to keep the noise level as low as possible, it is always advisable to use
very high-purity gas as the mobile phase.
9.2.3.
Stationary Phases
Chromatographic stationary phases are either solids or liquids coating or
bonded to solids. Common stationary phases are listed in Table 9.2. For gas
chromatography the solids are activated carbon of various sorts, polymers,
molecular sieves, or similar materials, and the chromatography may be
referred to as
gas-solid chromatography
(GSC). This type of stationary phase
