Introduction to Soil Chemistry
Introduction to Soil Chemistry
Introduction to Soil Chemistry
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gas chroma<strong>to</strong>graphy 179<br />
Figure 9.3. Sample application <strong>to</strong>ols from <strong>to</strong>p <strong>to</strong> bot<strong>to</strong>m, glass capillary, Pasteur pipette with tip<br />
drawn out, syringe for HPLC, and syringe for GC.<br />
Table 9.2. Common Stationary and Mobile Phases Used in Chroma<strong>to</strong>graphy<br />
Chroma<strong>to</strong>graphic Method Stationary Phases Mobile Phases<br />
Gas chroma<strong>to</strong>graphy Solid or inert solid covered Gas, usually helium,<br />
by high-boiling liquid a nitrogen, argon,<br />
or hydrogen<br />
High-performance liquid Fine porous silica and alumina; Same as liquid<br />
chroma<strong>to</strong>graphy particles are finer, increasing chroma<strong>to</strong>graphy<br />
efficiency but requiring but at high<br />
high pressure <strong>to</strong> push pressure<br />
elutant and sample<br />
through column b<br />
Thin-layer chroma<strong>to</strong>graphy Thin layer, commonly 250mm Aqueous and<br />
(applies also <strong>to</strong> paper thick, of silica gel, alumina, solvent<br />
chroma<strong>to</strong>graphy) cellulose, b or a sheet of solutions<br />
chroma<strong>to</strong>graphic paper<br />
Electrophoresis Solid or semisolid absorbant Current<br />
saturated with buffer<br />
a Oil can be varied such that the stationary phase has varying degrees of polarity.<br />
b Surface modifications commonly involve phases <strong>to</strong> change the surface polarity such as attaching<br />
a long-chain hydrocarbon, usually 18 carbons in length. This would be called a reverse-phase<br />
C18-impregnated stationary phase.
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