degasser, pump, autosampler and column oven—has been refined and optimized to deliver superior performance
specifically for GPC/SEC. For example,
the latest degasser design combines low
volume, which makes it easier to switch
between different solvent systems, with
the degassing performance needed to
secure high signal-to-noise ratios on
all detectors. New low pulsation pumps
deliver highly stable flow rates for
smooth experimental baselines, and also
have features such as integrated seal
back flushing that reduces seal wear and
allows use of high salt buffers without
increasing servicing requirements.
The latest autosamplers have zero
overhead injection, which means they
can inject the sample with no sample
waste. They also have the precise temperature control needed to ensure all
samples are maintained in an optimal
state. For example, proteins, which have
a tendency to aggregate, can be cooled
to protect them from degradation.
Successful analysis relies on maintain-
ing the sample at a closely controlled
temperature during both separation
and detection. For example, certain
polymers will dissolve only in relatively
high viscosity solvents. Here integrated
column ovens make it possible to run
at elevated temperature, to reduce the
solvent viscosity and the pressure in the
separation columns, thereby helping to
improve system performance.
As multi-detector arrays become
more widely used, there’s more focus on
ensuring these detectors work together
effectively. Although detectors can be
sourced individually, integrated arrays
offer a number of distinct advantages
(Table 2). These include:
• Detectors connected in a sequence
that optimizes the performance of each
• Reduced inter-detector tubing
lengths, to minimize band broadening.
• Precise temperature control over
the full detector array and connecting
As a result, an integrated detector array—such as in the OMNISEC
REVEAL—delivers more accurate
results and has higher sensitivity than
modular detector set-ups. As well as the
shift to integration, the performance of
individual detectors is also being substantially enhanced to meet evolving
For example, as a result of more efficient optics and advanced fiber connectivity, the latest light scattering detectors
are many times more sensitive than
older designs. This greater sensitivity
delivers more accurate measurements
for low molecular weight materials that
produce relatively weak light scattering signals, and provides more precise
analysis with smaller sample injection
volumes. As a result, the newest light
scattering systems deliver high performance across a wide range of molecular
weights and concentrations.
Increased sensitivity in the measurement of molecular weight and concentration calls for higher accuracy and
productivity in measurements made for
structural analysis. This requirement is
addressed in new viscometer designs,
where the use of a self-balancing mechanism ensures viscosity measurements
are made at optimum sensitivity. Productivity is also improved by the use of
user-exchangeable capillary modules
and user-selectable delay volumes,
which support the optimization of viscometer performance.
New levels of analytical
productivity and accuracy
GPC/SEC is an essential technique
for those working with macromolecules,
whether polymers, proteins or polysaccharides. Advances in GPC/SEC technology therefore have widespread impact
in polymer, food, pharmaceutical and
biopharmaceutical industries, as well as
in academic research. Recent innovations
have produced fully integrated separation and detection modules that break
new ground in critical areas such as the
accuracy and sensitivity of measurement,
instrument productivity, ease-of-use and
the management of the analytical workload
associated with achieving high-quality
data. Such improvements widen the field of
applications GPC/SEC can be successfully
used for, and have the potential to positively impact the efficiency of analysis in all
Product Marketing Manager, Nanoparticle
and Molecular Characterization
Detector type Features to look for Practical benefit
Refractive index Robust flow cell design. Enables first-in-series connection for improved stability
Temperature stability. Better baseline stability; improved sensitivity.
UV PDA designs that offer detection over the full
UV/Vis wavelength range.
Accurate concentration measurements for proteins and
other samples containing chromophores; detection and
quantification of different components in blends, copolymers or protein conjugates.
Light scattering Inclusion of RALS. Accurate measurement for low molecular weight samples.
Inclusion of LALS. Accurate and direct measurement for high molecular
Fiber delivered laser. Greater sensitivity for all measurements—greater accuracy with less sample.
Viscometer Automated mechanical bridge balancing. Optimized accuracy and sensitivity for each analysis.
User-exchangeable capillary module and delay
Easy user set-up and reduced downtime.
Robust, all stainless steel pressure transducers
with a wide operating range.
Ease-of-use—system is suitable for a very wide range of
solvent and buffer types.
Table 2: Improvements in detection: Summarizing the latest features
and the benefits they bring.