A convex “Ferguson plot” of polystyrene particles in electrophoresis on 0.25 to 2.0 % polyacrylamide (30 % Bis‐crosslinked)

Abstract

AbstractThe plot of log(mobility) vs. gel concentration for polystyrene particles of 26.9 and 44.2 nm radius in 30% Bis‐crosslinked polyacrylamide below 2.2 %T, containing 22.5% Metrizamide and 6 M urea, is convex. The convex plots of the two particles are essentially parallel. This parallelism suggests a retardation by a mechanism other than sieving. The parallel plots cover a range of polyacrylamide concentrations characterized by progressive fluidity as %T is lowered below 2 %T. The convex curvature renders suspect the previous free mobility and valence determinations in polyacrylamide gel electrophoresis obtained by linear extrapolation of Ferguson plots to 0 %T. Nonlinear extrapolation to 0 % T of plots of log(mobility) vs. gel concentration in the concentration range below 2 %T of 30% Bis‐crosslinked polyacrylamide for the two polystyrene particles, corrected for the effects on mobilities of Metrizamide, urea and a lower ionic strength, provides free mobility values similar to those obtained under otherwise identical conditions on agarose gel electrophoresis.