title: Ionic concentration- and pH-dependent electrophoretic mobility as studied by single colloid electrophoresis.
abstract: Optical tweezers are employed to measure separately the complex electrophoretic mobility of a single colloid and the complex electroosmotic response of the surrounding medium in a specially designed microfluidic cell. Using the very same colloid both quantities are determined in dependence on the concentration of the aqueous salt solution (10 (- 5)-10 (- 1) mol l (- 1)), the valence of the ions (K (+) , Ca(2 +) ) and the pH (2.5-8.5). A pronounced effect is observed for all these examined parameters. The dependence on ion concentration agrees qualitatively-for the monovalent case-with the predictions of the standard electrokinetic model.
authors.affiliation: Institute for Experimental Physics I (MOP), University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Semenov
authors.forename: P
authors.initials: P
authors.lastname: Papadopoulos
authors.forename: G
authors.initials: G
authors.lastname: Stober
authors.forename: F
authors.initials: F
authors.lastname: Kremer