Aqueous Size-Exclusion Chromatography

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This project, supported in the Analytical and Surface Chemistry Program, involves the continuation of an experimental and molecular modeling research program studying solute retention phenomena in size exclusion chromatography (SEC). Professor Paul L. Dubin and his students at the Indiana University - Purdue University at Indianapolis have selected various model compounds of defined geometry that are indicative of spherical and asymmetric solutes which exhibit ideal and non-ideal elution characteristics on porous glass SEC stationary phases. The impetus of this study is to derive rigorous theoretical relations which correlate the chromatographic partition coefficient of various solutes with their size and geometry. In addition, Professor Dubin will incorporate electrostatic effects to model protein separation by SEC. The retention characteristics of several highly purified model proteins will be measured at Superose 12 stationary phases. Electrophoretic light scattering and capillary zone electrophoresis techniques will also be used to characterize high molecular weight analytes. Aqueous size exclusion chromatography is commonly used to assay molecular weight distribution and identify mixtures of complex synthetic and natural water soluble polymers. Retention order in this technique is based on the size based partitioning of analyte throughout varying sized pores of the stationary phase, with those solute having geometries equivalent to that of the packing being retained longer on the column. However, in cases where geometric considerations do not solely govern interactions between the solute and the stationary phase, the retention characteristics of analytes at SEC stationary phases can be quite different from that of the calibration standard, which can lead to gross errors in the measurement. Prof. Paul Dubin and his students at Indiana University will use various model compounds and molecular modeling algorithms to derive a fundamental retention theory which relates retention of polymeric solute with solute size.