Handbook of Size Exclusion Chromatography and Related ...

Figure 1 Chromatogram showing SE/HdC separation of narrow polydispersity
polystyrene standards. Column: two 300 7:5mm PLgel Mixed-E columns in series;
flow rate, 1.0mL/min. A ¼ 4,000,000; B ¼ 1,550,000; C ¼ 550,800; D ¼ 156,000;
E ¼ 66,000; F ¼ 30,300; G ¼ 9200; H ¼ 3250; J–Q ¼ oligomers; R ¼ 162; S ¼ toluene.
(From Ref. 1.)
2 HYDRODYNAMIC CHROMATOGRAPHY
The basic principles of HdC are easily explained by considering the transport of
spherical macromolecules in laminar flow through an open microcapillary tube
(Fig. 3). The solvent velocity profile in an open tubular tube is aparabolic
Poiseuille flow.Macromolecules are considered as rigid spheres and are neutrally
buoyant. As a result of Brownian motion, macromolecules will disperse
throughout the capillary cross-section. Because of their finite sizes, the centers of
thepolymermoleculescannotapproachthecolumnwallanycloserthantheirown
radii. Owing to the fluid velocity profile, alarger solute molecule travels through
thecapillaryatagreateraveragevelocitythanasmallersolute.Inotherwords,the
separation of HdC is not due to size exclusion itself, but to the faster average
© 2004 by Marcel Dekker, Inc.