CARBOXYLATED STARBURST DENDRIMERS AS CALIBRATION STANDARDS FOR AQUEOUS SIZE EXCLUSION CHROMATOGRAPHY

Standards commonly employed to calibrate size exclusion chromatography columns usually do not themselves have well-defined sizes. Carefully characterized spherical solutes in the apporpriate size range are therefore of considerable interest. The chromatographic behavior of carboxylated starburst dendrimers-characterized by quasielastic light scattering and viscometry-on a Superose size exclusion column has been explored. Carboxylated starburst dendrimers appear to behave as noninteracting spheres during chromatography in the presence of an appropriate aqueous mobile phase. The dependence of the retention time on solute size seems to coincide with data collected on the same column for Ficoll, an uncharged, quasi-spherical polysaccharide. Chromatography of the dendrimers yields a remarkable correlation of the chromatographic partition coefficient with the generation number; this result is in part a consequence of the exponential relationship between the generation number and the molecular volume of the dendrimers.