ver.211025E
SHOWA DENKO K.K. (https://www.shodex.com/)
3
· Shear degradation is more likely to occur in larger molecular weight compounds. When
shear degradation occurs, the measured molecular weight may be lower than the actual
value or it may influences the repeatability of the analysis. If shear degradation is
suspected, use a lower flow rate.
5. Eluent Preparation
(1) Degas the eluent fully to prevent the formation of air bubbles.
(2) Presence of small debris or insoluble substances may result in deterioration of the column and/or they appear
as noise on the chromatograms. Filter the eluent with a 0.45-
μ
m disposable filter to prevent the problems.
Attention!
· Whenever water is required, use ultra-pure water freshly generated by a water purification
system or water from a newly opened HPLC grade distilled water bottle. Use HPLC grade
organic solvent whenever possible. Solvents left in an opened bottle for a long time should
not be used. The content may have been changed, absorbed moisture, or has been
contaminated.
· Always use freshly prepared solvents. Solvents stored for a long time may have changed
their compositions and may influence elution patterns and/or damage the column.
Note
· Use of on-line degasser is recommended.
6. Sample Preparation
(1) If possible, use the eluent for analysis to dissolve or dilute samples. If this is difficult, use a solvent which
has a composition that is as close as possible to the eluent's composition, but which fully dissolves or dilutes
the sample.
(2) Filter the sample solution using disposable 0.45-
μ
m filter to prevent the column from clogging or deteriorating.
(3) To prepare a sample with molecular weight larger than 1,000,000, first allow the sample to stand in the eluent
of analysis for 1 day until it becomes fully swollen. Next, slowly agitate the sample solution to completely
dissolve the sample. Be careful as aggressive agitation can cut the polymer chains of the analyte.
(4) Recommended injection volume is
250 - 1,000
μ
L per column.
(5) Viscosity of high molecular weight compound is largely influenced by its molecular weight and concentration.
Samples with high viscosity cause peak broadening and elution delay, and this makes it difficult to obtain
their accurate molecular weight distributions. In general, the larger the molecular weight of the compound,
the higher its viscosity becomes. To suppress the influence from high viscosity, it is recommended to lower
the sample concentration. Please use the below table as a reference when preparing samples for molecular
weight distribution analyses.
Molecular Weight Range
Optimal Concentration (w/v)
≤
5,000
≤
1.0 %
5,000 - 25,000
≤
0.5 %
25,000 - 200,000
≤
0.25 %
200,000 - 2,000,000
≤
0.1 %
2,000,000
≤
≤
0.05 %
Note
· Use of guard column is recommended to protect the analytical column.