The retention of both underivatized and carboxylated polystyrene latex beads by electrical field-flow fractionation (EIFFF) was investigated using a 2 mM aqueous solution of quinonehydroquinone as the carrier liquid. The quninone-hydroquinone redox couple passes current with less polarization of the electrodes than carrier liquids previously employed. Underivatized beads, ranging in diameter from 0.15 to 0.74 #x3BC;m eluted in the normal mode, while carboxylated beads larger than 1 #x3BC;m eluted in the steric mode. Normal mode retention increases with flow rate, probably due to shearing of the polarization layer, which increases the working field. At a constant field and flow rate, normal-mode retention is inversely related to the product of a particle's size and electrophoretic mobility, in accordance with retention theory. Thus, ElFFF can be used to obtain both the size and electrophoretic mobility of particle suspensions.
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