Handbook of Size Exclusion Chromatography and Related ...

solvent speed in the area where the macromolecules (or particles) are restricted due
to their size.
HdC separation also occurs in the interstices of a packed column, although
the configuration of channels is not as simple as in a microcapillary tube. Owing to
the three-dimensional void structure of a packed column, the exact form
of the velocity profile is not clearly defined as it is in the microtubular columns. The
mechanism is much more complicated than for an open tubular HdC. However, we
may consider these voids as a set of equivalent capillaries. Bird et al. (4) found that
the radius of equivalent capillaries is roughly 0.2 times the mean diameter of the
packing beads.
Most current liquid chromatographic columns, including SEC and HPLC,
are packed with porous gels. With porous packings, SEC separation is more
noticeable than HdC separation. A pure HdC separation can be demonstrated
using a column packed with nonporous solid gels. Figure 4 shows an example
of an HdC chromatographic separation using 1.50mm solid beads (5). The
calibration curves of polystyrene standards separated in THF mobile phase with
Figure 4 High-speed packed column HdC separation of polystyrenes dissolved in THF.
Column, 150 4:6mm; packing, 1.50mm nonporous silica particles; pressure drop,
200bar; detection, UV. (1) PS 775,000, (2) PS 336,000, (3) PS 127,000, (4) PS 43,900, and
(5) toluene, 0.2mg/mL each. (From Ref. 5, Copyright 1993, Elsevier.)
© 2004 by Marcel Dekker, Inc.