Liquid chromatography of macromolecules under limiting conditions of adsorption. I. Principles of the method

A novel separation method for macromolecules, viz. liquid chromatography under limiting conditions of adsorption (LC LCA), is presented. LC LCA is designed for discrimination of complex polymers. It combines exclusion and adsorption mechanisms so that they mutually compensate. This results in the absence of separation of macromolecules according to their size or molar mass. In LC LCA, the eluent is a liquid moderately promoting adsorption of polymer species. The column packing attracts macromolecules and, if the sample were dissolved and injected in eluent, it would be retained within column. Therefore, the polymer is injected in a solvent that effectively suppresses adsorption. Experimental conditions can be identified with regard to the eluent, column packing, temperature as well as sample solvent, and injected sample volume under which macromolecules of various molar masses are eluted together with their initial solvent. In this way, binary polymer blends, with components exhibiting different adsorptive properties can be separated. The LCA behavior of poly(methyl methacrylate) is presented using bare silica gel or "active" polystyrene/divinyl benzene column packings, tetrahydrofuran as desorption promoting liquid and toluene or chloroform as adsorption promoting liquids.