Swelling kinetics of immobiline gels for isoelectric focusing

The possibility of polymerizing Immobiline gels by a batch procedure and then storing them dry for subsequent use has been investigated. The gel swelling kinetics have been studied as a function of the following variables: a) solvent composition (plain water, 8 M urea, 2% Nonidet P‐40 and their mixture); b) gel composition (varying %T at fixed %C); c) temperature (in the range 20–60°C); d) gel thickness (from 0.5 to 2 mm); e) operative pH interval (from the extreme acidic, pH 3.5‐5, to the extreme alkaline, pH 8.5–10, ranges) under isoionic strength conditions. The following practical guide‐lines for gel drying should be observed: a) the gels should have a low matrix content (3 %T or lower); b) they should have reduced thickness (0.5, max. 1 mm); c) alkaline gels should be dried in vacuo over silica, to prevent CO 2 absorption; d) the gels should be extensively washed prior to drying. Swelling kinetics are discussed in terms of Langmuir adsorption isotherms, while the diffusion of water in Immobiline gels does not seem to follow a passive Fickian mechanism.