| GEL FILTRATION
CHROMATOGRAPHY (GFC): A form of Size-Exclusion
Chromatography (SEC)
using aqueous mobile phases and hydrophilic stationary phases. Commonly used
for separations of proteins or nucleic acids on the basis
of molecular size.
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| GEL PERMEATION
CHROMATOGRAPHY (GPC): A form of Size-Exclusion
Chromatography (SEC)
using organic mobile phases and hydrophobic stationary phases. Commonly used
for separations of synthetic polymers on the basis of
molecular size.
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| GRADIENT ELUTION:
an HPLC procedure where the composition of the mobile
phase changes during the separation. For example, the
mobile phase starts out as water, and methanol is added
continuously so that the percent methanol in the mobile
phase increases from zero to 100% during the run. See
also ISOCRATIC.
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| GRAM (g): a unit of
mass, equal to about 0.03 ounces. See Section 4B for the relationship to other units
of mass.
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| GUARD COLUMN: a
short column placed between the sample injector
and the inlet of the main ("analytical") column;
the guard column is packed with the same kind of packing
as the main analytical column, and is intended to absorb
or pick up impurities in the sample or mobile phase that
might damage the main column.
|
 Protecting the Analytical Column
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