A Derived Moving Reaction Boundary Initially Created by Formic Buffer and Sodium Hydroxide in Capillary Electrophoresis: Theoretic and Experimental Study

In this article, we investigate a derived moving reaction boundary (MRB) generated upon current application in a discontinuous electrolyte system consisting of formic buffer (anolyte) and sodium hydroxide (catholyte). The model showcases the formations of two derived zones, including an acidic zone (Zone β1) and an alkaline zone (Zone β2), and the subsequent development of a derived MRB between Zones β1 and β2. The proposed model was validated through numerical simulations and experiments using capillary electrophoresis and gel-based visualization, with insulin and phenylalanine selected as model analytes. Quantitative comparisons demonstrate good agreement between the derived MRB theory and experimental observations, whereas the conventional model fails to accurately predict the observed boundary behavior. This work provides new insights into reaction boundary dynamics in weak acid-strong base electrolyte systems and offers practical guidance for sample stacking strategies in peptide and protein electrophoresis.