Particle Sedimentation in pH-Gradients.

A new method is explored, where charged colloidal particles are sedimented in a pH-gradient, and an application in following the sedimentation velocity behavior of colloidal gold particles with cationic resp. anionic charge in a pH-gradient is described. A procedure to analyze this type of experiment is developed, where the effects of the changing pH and other parameters resulting from a pH-gradient onto sedimentation are considered. This qualitative analysis allows an understanding of charge effects on the sedimentation behavior of colloids in a preformed pH-gradient and suggests ways for future quantitative evaluation of such data towards the determination of particle charge distributions. [ABSTRACT FROM AUTHOR]