PARTICLE TRAJECTORIES IN FIELD-FLOW FRACTIONATION AND SPLITT FRACTIONATION CHANNELS

The need for particle trajectory determination within field-flow fract ionation and SPLITT fractionation channels is discussed. In the case o f steric or steric/hyperlayer FFF, the trajectory followed by a partic le determines its elution time. With hydrodynamic relaxation, the dete rmination of a representative set of trajectories can also provide inf ormation on the band spreading inherent to the technique. In the simpl est case of SPLITT fractionation where a binary separation is the obje ctive, the trajectories determine the point at which a separative cut is made, as well as the sharpness of the cut. The influence of hydrody namic lift forces, applied transverse and longitudinal fields, and sec ondary crossflow on particle migration are discussed, as well as the p erturbing influence of the presence of the channel walls. Finally, a c omputer program is used to generate sets of particle trajectories to i llustrate certain aspects of the preceding discussion.