A method for forming internal pH gradients in chromatographic column filled with a carboxylic cationite

Chromatofocusing was used to form descending pH gradients inside a column packed with a cationite based on supercrosslinked polystyrene with carboxy groups. The column was preliminary equilibrated with a starting buffer solution (10 mM Tris-HCl) to pH 7.5. It was demonstrated that pH gradients can be formed using buffer eluents containing a carboxylic acid or an amino acid as the active component. In the system under study, pH gradients with a high degree of linearity can be obtained when a strong electrolyte (NaCl) is added to the eluent and starting solution.