Moving reaction boundary and isoelectric focusing: IV. Systemic study on Hjertén's pH gradient mobilization.

In this paper, Hjertén's mobilization of pH gradient in IEF was systemically and quantitatively analyzed with the R(r )value of judgment expression comparing the fluxes of hydrogen and hydroxyl ions. The theoretical results show that (i) there is R(r) = 0, viz., quasi-equal fluxes of proton and hydroxyl ion, in a classic IEF with sulfuric acid and sodium hydroxide used as the anolyte and catholyte, respectively, this is the main reason why pH gradient is quite stable in IEF; (ii) but if the salt of sodium sulfate is added into the sodium hydroxide, there is R(r) > 0, viz., the flux of proton being higher than that of hydroxyl ion, the R(r) value implies a cathodic mobilization of pH gradient, and the higher the R(r )value is the faster the cathodic mobilization becomes; (iii) if the salt is added into the sulfuric acid, there is R(r) < 0, the R(r) value indicates an anodic mobilization, and the smaller the R(r) value is the faster the anodic mobilization turns. To test these theoretical results above, a novel procedure was developed for the run of classic IEF followed by Hjertén's mobilization of pH gradient. The strict experiments were in well coincidence with the theoretical results. The results have obvious significances for the mechanism and development of Hjertén's mobilization.