Entropic Contribution to the Retention of Nonspherical Particles in Field-Flow Fractionation

✍ Scribed by Ronald Beckett; J.Calvin Giddings

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 177 KB
• Volume: 186
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1996.4612

✦ Synopsis

The purpose of the field in FFF is to drive the suspended In this paper the effect of particle shape on the entropy of particles across the thin dimension of the channel toward nonspherical particles adjacent to a plane surface is considered. one of the channel walls (the accumulation wall). In the The subsequent influence on particle retention in field-flow fracnormal mode of separation, particles are considered as small tionation (FFF) has been estimated. New retention equations for masses undergoing vigorous Brownian motion such that conthin rod and disc shaped particles have been derived to cover this centration diffusion balances the flux induced by the applied steric-entropic region of FFF. As particle size increases relative to field driving the sample toward the accumulation wall. In the mean cloud thickness, the retention ratio for nonspherical these circumstances each sample component will achieve an particles is predicted to increase compared to small spherical partiequilibrium cloud structure adjacent to the accumulation cles of the same mass. This could result in a significant underestimation of the calculated equivalent spherical diameter (d) by FFF wall which is characterized by an average cloud thickness methods. The steric-entropic FFF equations could be used to calcul. Different components (consisting of particles of a given late accurate d values if the large particle dimension is estimated type and size) with different l values are then carried along independently (e.g., by microscopy). Alternatively, run conditions the axis of the channel at unequal velocities by channel could be designed to minimize steric-entropic perturbations to the flow, leading to their separation. The unequal velocities arise ideal retention equation.