Structure parameters of molecules and media evaluated by chromatographic partition: I. Controlled-pore glasses

Abstract

Polystyrene, dextran and sodium dodecyl sulphate—protein data for eleven controlled-pore glasses have been used to validate the expression K D = ( b − R e/ R x) 2 derived from a geometrical exclusion model for cylindrical pores. The calculated pore radii ( R x) agreed well with mercury-intrusion values, and the crucial role of Stokes′ radius ( R e) was confirmed by comparison with Casassa's formulations [E.F. Casassa and Y. Tagami, Macromolecules, 2 (1969) 14; E.F. Casassa, J. Polym. Sci., Part B, 5 (1967) 773]. From theory it was demonstrated that for any molecule, R e = A M x where A and x are defined, structure-specific constants. Thus, linear K D( M) functions were derived and tested, by which one is able to distinguish between coils. rods and ellipsoids, ideal and real solvents, and to determine bond lengths, expansion, gyration radii, axial ratios and diffusion coefficients. The characteristic shape of the empirical K D:log M curves derives directly from the linear K D( M) function.