ELECTRICAL FIELD-FLOW FRACTIONATION - A TOOL FOR CHARACTERIZATION OF COLLOIDAL ADSORPTION COMPLEXES

The theoretically predicted inverse relationship between the retention parameter lambda for electrical field-flow fractionation (FFF) and a sample's particle diameter d is verified experimentally using colloids of well-characterized size and electrophoretic mobility. From observe d retentions of these samples, it is possible to experimentally determ ine the magnitude of the effective field operating in the channel at a ny particular time. Even minor amounts of adsorbed nonionic polymer ar e shown to significantly reduce the retention of a polystyrene carrier particle, indicating that retention in electrical FFF might be a sens itive reflection of changes in surface composition for colloidal mater ials. With knowledge of the effective field, an observed retention is shown to provide information regarding a sample's electrophoretic mobi lity, provided outside size information can be obtained. (C) 1997 John Wiley & Sons, Inc.