Bio-Rad Aminex Organic Acid and Alcohol Analysis Columns - Manual (Page 3)

Section 1
Introduction to Resin-Based HPLC Columns
Resin-based HPLC columns use the mechanisms of ion exclusion, ion exchange,
ligand exchange, size exclusion, reversed phase, and normal phase partitioning.
These multiple modes of interaction offer a unique ability to separate compounds.
The charge on the resin provides the capability for ion exclusion, while the
polystyrene backbone allows hydrophobic interaction to take place. The extent of
the interactions depends on the compounds being analyzed and the degree of
selectivity required.
Reversed phase and ion pairing HPLC techniques require complex eluant conditions
for effective separations. These methods work on the principle of modifying the
compound to be analyzed until it is compatible with the column. With resin-based
HPLC columns, instead of modifying the compound to be analyzed, the column
packing material is modified and chromatographic conditions are optimized to be
compatible with the compound structure. Therefore, resin-based columns often allow
the use of an isocratic HPLC system, they simplify sample preparation methods, and
they require no sample derivatization. By cutting down sample preparation time,
resin-based columns greatly reduce total analysis time. Filtration is the only sample
preparation necessary in most separations.
The column is the heart of the high performance liquid chromatographic system.
The success or failure of the analysis often depends on selecting proper operating
conditions and on maintenance of the column. No matter how good the HPLC
system performance and the sample preparation are, successful separations may
not result if the column is not functioning properly.
The packed bed is a depth filter, and thus it is an excellent collection device for
particulate matter. The smaller the packing media, the better it acts as a filter. The
bonded resin column packings are suitable for separating certain solutes, but are also
capable of retaining other components of the sample indefinitely. These retained
compounds may significantly decrease column efficiency and selectivity. If proper care of
the column is not taken, then time and money are wasted, since a good column may be
ruined in a short amount of time. It is extremely important to take the time required to do
any column maintenance which will keep problems to a minimum. With the proper
set-up, proper maintenance, and good laboratory technique, the column will not lose
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