A STUDY OF DENDRIMER-SOLUTE INTERACTIONS VIA ELECTROKINETIC CHROMATOGRAPHY

Polyacid cascade dendrimers (generations 1-4) are used as a pseudostat ionary phase for electrokinetic capillary chromatography to separate m ixtures of neutral species. Separation of a homologous series of molec ules allow the capacity factors and distribution coefficients to be ca lculated, which in turn allow the standard enthalpy, entropy, and Gibb s free energy for solubilization to be evaluated by van't Hoff analysi s. Comparison of these values to analogous values measured for sodium dodecyl sulfate (SDS) micelles suggests fundamental differences in the thermodynamic quantities associated with solubilization. As the size of the polyacid dendrimer increases, entropy becomes the driving force for solubilization, and enthalpy is disfavored. Gibb's free energy va lues are negative for: all of the dendrimer/analyte interactions inves tigated. The capacity factor is found to increase linearly with increa sing concentrations of dendrimer. Thermodynamic parameters are evaluat ed for several small molecules to show that the technique is not limit ed to molecules that are part of a homologous series.