Field-flow Fractionation in the Hyperlayer Inversion Region.
Keith D. Jensen.
Senior Honors Thesis for the Honors Degree of Bachelor of Science in Chemistry, University of Utah, (1993).


Separation by crossflow-hyperlayer field-flow fractionation (FFF) is extended well below the normal limit of 1 Ám to include particles 0.24 Ám in diameter and larger. An example of coelution of different sized particles, the major complication of the hyperlayer inversion, is included. A mixture of four polystyrene latex particle standards ranging in size from 2.062 Ám to 0.300 Ám is separated in the hyperlayer mode with baseline resolution in under three minutes. A fast normal mode separation of four polystyrene particles is also separated with baseline resolution in less than three minutes. The hyperlayer inversion diameter is lowered by increasing the force of the applied field and hydrodynamic lift-forces which focus the eluting particles into thin bands which elute in the hyperlayer mode. The applied field is increased in flow FFF by increasing the cross flowrate. Increasing the channel flowrate and decreasing the channel breadth and width increase the shear rate which increase the lift forces.

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