An Extended Range of Columns for Aqueous Size Exclusion Chromatography
Inspiring Excellence™
Greg Saunders, Graham Cleaver and Ben MacCreath, Varian, Inc., Church Stretton, Shropshire SY6 6AX, UK
Introduction
PL aquagel-OH Range for Aqueous SEC
This poster describes an extensive family of columns for aqueous size
exclusion chromatography. The columns are packed with materials of high
hydrophilicity to ensure pure SEC is obtained for the widest range of
samples, including anionic, cationic and hydrophobic types. Being available
in many particle and pore sizes, this newly completed range of columns
represents a versatile solution to aqueous SEC.
Size exclusion chromatography (SEC), also known as gel permeation
chromatography (GPC), is an important analytical technique in the field of
polymer analysis. Using SEC, samples of polymer are separated on the
basis of size in solution. Assuming an appropriate calibration is performed or
specific information-rich detectors are selected, the size separation can be
converted into a molecular weight separation - key information in describing
the physical behavior of the polymer. Aqueous SEC is used for the analysis
of water-soluble polymers. Recently, there has been increasing interest in
this area as the development of biodegradable and environmentally friendly
materials has grown.
The use of SEC for the analysis of aqueous polymers is of growing interest.
However, this application area is challenging due to the number of ionic and
hydrophobic interactions that can occur when analyzing water soluble
materials. PL aquagel-OH columns have been specifically designed to allow
the analysis of materials of this kind. Simple modification of the eluent
minimizes interactions and ensures that pure size exclusion
chromatography is obtained.
Size Exclusion Chromatography
SEC is a technique used for the separation of
macromolecules on the basis of their size in
solution. A sample is introduced into a flow of
solvent passing through a column packed with
porous beads. As the molecules pass down the
column they are able to diffuse in and out of the
pores, dependent on their relative dimensions. As
a result, smaller molecules, (lower molecular
weight) are retarded in eluting from the column
compared to larger molecules (higher molecular
weight). Thus a size separation is obtained.
Typically, SEC columns for aqueous applications require packing materials
with highly hydrophilic surfaces that are compatible with water and buffers.
Particle sizes must be tailored to allow high-resolution separations to be
performed without undue increase in column backpressure that can lead to
shearing effects and can reduce the column lifetime. Finally, as the range of
applications grows a very large array of columns is required to cover all
possible sample types across the range.
Typical Standard Separations
The PL aquagel-OH range of
columns can be calibrated in
aqueous eluents by the use of
polyethylene glycol and oxide
(PEG/PEO) standards, or with
pullulan polysaccharaides.
Features of the PL aquagel-OH
range:
PEG/PEO standards are suitable
for a wide range of applications,
whereas
the
polysaccharide
standards are more suited to the
analysis of biological sugarbased materials as they are
similar in structure and therefore
give more realistic results.
• pH range 2 – 10
• Compatible with 50% methanol
• High mechanical stability
• 8 μm columns for analytical work
• 15 µm for high viscosity polymers
• 5 µm for high resolution analysis
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Characteristics of the full PL aquagel-OH Range
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Typical applications
Heparin
is
a
highly-sulfated
glycosaminoglycan
with
a
low
molecular weight which acts as an
anticoagulant. The molecular weight of
Heparin influences the clotting of the
material. PL aquagel-OH columns may
be used to distinguish different batches
of this material.
Hyaluronic acid is a naturally
occurring polysaccharide that
is extracted from the combs of
roosters. Used in eye surgery
due to its superior viscosity
properties,
the
molecular
weight distribution is critical to
the medical application of this
material.
Pectin is a structural polysaccharide
found in the walls of cells. It is
extracted from citrus fruits and used as
a gelling agent in food. Molecular
weight is a key parameter of this
material, controlling the viscosity
properties.
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Chitosan is a polysaccharide
produced from chitin, the main
component of crab shells.
Chitosan has received interest
due to it’s susceptibility to
biodegradation.
A cationic
material, chitosan must be
dissolved in concentrated acid
for analysis and must be
analyzed at low pH to obtain
good chromatography.
Polyacrylamide is a synthetic
polymer that has uses as a
thickening agent and in gel
electrophoresis. Generally a
high molecular weight material,
the analysis of polyacrylamide
requires large particle size
columns due to the viscosity of
the material.
The PL aquagel-OH range of columns
covers
applications
across
the
molecular weight resolving range.
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Summary
The analysis of water-soluble polymers by SEC is difficult due to the number
of ionic and hydrophobic polymers that can be dissolved in water. The PL
aquagel-OH column range is an extensive selection of columns specifically
designed for the analysis of water-soluble polymers. Available in a range of
pore and particle sizes, the PL aquagel-OH range provide solutions for all
aqueous SEC appications.
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