Collect. Czech. Chem. Commun. 1998, 63, 155-163

Isoperichoric Focusing Phenomena Generated by Coupled Electric and Gravitational Field Forces in Bidisperse Mixtures of Colloidal Particles

Josef Janča and Natalia Gospodinova

Université de La Rochelle, Pôle Sciences et Technologie, Avenue Marillac, 17042 La Rochelle Cedex 01, France


The first successful isopycnic focusing generated by the coupled electric and gravitational fields applied to the model bidisperse mixtures of the colloidal silica and polyaniline particles of low size ratio is described. The theoretical analysis and the experimental results show that the density gradient forming liquid should not necessarily behave as a continuum regarding the focused species. This finding confirms the original prediction which was evidenced previously by the focusing under the action of high intensity centrifugal field forces only.

Keywords: Isopycnic focusing; Bidisperse colloidal suspension; Colloidal silica density gradient; Colloidal polyaniline composite suspension.