Handbook of Size Exclusion Chromatography and Related ...

Such an ideal separation can be obtained by connecting a10mm solid-bead
column and aPLgel Mixed-bed Dcolumn in series. The calibration curve of PS
standards is shown in Fig. 9. It is surprisingly almost perfectly linear, even up to
thehighestMW standard,7:5 10 6 .According toFig. 8,thecurvemay belinear
toamuchhigherMWregion.ThechromatogramsoftwoPSstandardmixturesare
showninFig.10.Theshapesofthe7.5 10 6 and2.56 10 6 peaksaresharpand
considerably less tailing than in aregular SEC chromatogram.
Abroad MW distribution sample was studied using both SEC alone and
SEC/HdC. These chromatograms are compared in Fig.11. This sample is largely
excluded from a typical mixed-bed SEC column, such as PLgel Mixed-B columns.
There is better separation with the SEC/HdC column; the entire sample is within
the separation range.
The above example demonstrates the feasibility of combining SEC and HdC
in one chromatographic run with a linear calibration curve. It would be more
convenient to use a mixed-bed packing that combines the separation mechanisms
of these two columns in one column. The recipe for such a packing can be
calculated according to the above study: (1) 10mm particle size, (2) with pores of
size distribution similar to PLgel’s Mixed-D column, and (3) a total pore volume
of about 40% of a regular SEC packing material. This configuration can also be
obtained by mixing 60% of 10mm solid bead with 40% mixed-D gels. Efforts are
under way to make such an ideal SEC/HdC packing.
ACKNOWLEDGEMENTS
The author expresses his appreciation to Noveon, Inc., for permission to publish
this article and for support on all research work, to Dr. C. S. Wu for his
encouragement and discussion, and to D. Hanshumaker for his help in preparation
of this article.
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7. Polymer Laboratories, Chromatography Products, Issue 2 2001/2002, p 14.
8. Polymer Laboratories, Chromatography Products, Issue 2 2001/2002, p 5.
© 2004 by Marcel Dekker, Inc.