Sieving matrices in capillary electrophoresis: Inflection slope and double reciprocal plot

We propose the use of a double reciprocal plot of the inflection slope and the concentration of a sieving polymer to compare sieving properties of polymers regardless of their concentration and to permit selection of appropriate sieving materials. Using this plot, the lines extrapolating the experimental values intersect the ordinate at the value corresponding to the inflection slope at the infinite concentration of the sieving polymer and the abscissa at the value characteristic for the given polymer. The latter corresponds to the polymer concentration at which the inflection slope equals half the inflection slope at an infinite polymer concentration. It is inversely proportional to intrinsic viscosity and this makes intrinsic viscosity an important physicochemical constant suitable for selection of new potent sieving polymers.