On-line coupling of flow field-flow fractionation and multiangle laser light scattering for the characterization of macromolecules in aqueous solution as illustrated by sulfonated polystyrene samples.

Seven sulfonated polystyrene standards (18 000-3 000 000 g/mol), taken as model substances for macromolecular polyelectrolytes, were dissolved in aqueous 0.1 M sodium nitrate solution and characterized by multiangle laser light scattering coupled on-line to flow field-flow fractionation. The distributions of molar mass and root mean square radius and the diffusion coefficients were obtained for each sample using a constant field of force for separation. Relationships between molar mass and root mean square radius [〈R(G)(2)〉(z)(0.5) = (2.71 × 10(-)(2))M(w)(0.56)] or diffusion coefficient [D = (7.10 × 10(-)(8))M(w)(-)(0.68)] were calculated. To investigate the static analytical range of this novel hyphenated technique a mixture of all seven samples was fractionated applying a programmed field. The relationship obtained between root mean square radius and molar mass was used to calculate a Mark-Houwink equation [[η]calcd = (2.99 × 10(-)(2))M(w)(0.68)]. To verify this result, the intrinsic viscosities for all samples were measured at low shear rate and found to be in good agreement [[η]calcd = (2.77 × 10(-)(2))M(w)(0.67)].