Near-wall field-flow fractionation : Application of surface forces and transversal voltage to fractionation in laminar flow
✍ Scribed by S.N. Semyonov
- Publisher
- Elsevier Science
- Year
- 1988
- Tongue
- English
- Weight
- 551 KB
- Volume
- 446
- Category
- Article
- ISSN
- 1873-3778
No coin nor oath required. For personal study only.
✦ Synopsis
A theoretical
analysis is presented of the motion and spreading of a probe containing particles in a transversal potential field. This arises in the vicinity of the flat channel walls as a laminar flow of carrier fluid moves in the channel. Parameters that characterize the process of fractionation in such a system and a system upon application of a transversal voltage were calculated. It is shown that the transversal electric field increases the fractionation efficiency. Also near-wall interactions can affect the process of electric field-flow fractionation.
Many articles have been devoted to the problems of particle fractionation in a stream of eluent with a transversal force acting on the interface between the solid and liquid phase. Capillary hydrodynamic chromatography', energy-barrier chromato-graphy2g3 and adsortion chromatography on glasses4 are in a state of development. In the papers cited, the interaction of the separating particles in the vicinity of the capillary walls or near the surface of the beads of the column packing, and the changes in particle concentration across the flow in this field, are discussed. Considering this kind of interaction, we can divide the potentials of the near-wall forces into three major groups.
(1) The repulsive near-wall potential. This is realized when the near-wall interaction energy has its greatest value on the wall, as is the case in capillary hydrodynamic chromatography of particles with sizes much smaller than the size of the cross-section channel.
(2) The attractive potential. This is realized when the potential energy minimum is positioned near the wall, or has its lowest value on the wall. This is almost the case in adsorption chromatography on glasses.
(3) The attractive potential with a potential barrier. This is different from case 2 in that the maximum in the profile depends on the potential energy. It is positioned such that the potential well near the wall is separated from the channel volume by the potential barrier. The possible application of this potential energy profile has been investigated in papers on energy-barrier chromatography.