Stagnant pore-blocked supports for improved extraction chromatography

Abstract

Prior work has demonstrated that the complex pore structure of the polymeric supports employed for the preparation of commercial extraction chromatographic resins is a major contributor to their poor column efficiency and susceptibility to pronounced peak tailing. Particularly problematic is the presence of a number of small, relatively inaccessible (“stagnant”) pores. By blocking these pores with an appropriate inert filler, the extractant can be confined to the more readily accessible intermediate and large pores. The result is improved column efficiency (i.e., up to a 40% increase in N), reduced peak tailing and asymmetry (i.e., up to a 34% reduction in As), and in some instances, higher metal ion uptake capacity (up to a 64% increase) versus a commercial resin. The utility of the improved chromatographic performance arising from this “stagnant pore blocking” is illustrated in the separation of selected trivalent lanthanide ions, specifically Nd(III) and Eu(III), whose resolution has been reported to be unsatisfactory using conventional extraction chromatographic materials.