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].