COIL DIMENSIONS AND CONFORMATION OF MACROMOLECULES IN AQUEOUS-MEDIA FROM FLOW FIELD-FLOW FRACTIONATION MULTI-ANGLE LASER-LIGHT SCATTERING ILLUSTRATED BY STUDIES ON PULLULAN/

For a comprehensive description of the steric structure of macromolecu les, which includes molecular shape as well as coil density and flexib ility, a novel analytical technique for aqueous systems is introduced. The reliability of the method is illustrated by investigations on nar rowly distributed pullulan standards in the molar mass range from 10(5 ) to 10(6) gmol(-1). Hydrodynamic information (D, R(D)) was yielded by flow field-flow fractionation, while simultaneous scattering experime nts delivered the corresponding 'static' dimension R(G) and molar mass M. The observed asymmetry-factor was R(G)/R(D)=1.7 With increasing mo lar mass the mean coil density rho(Pol) decreased from 19.1 to 2.6 mg ml(-1) and the calculated persistence lengths l(p) increased, ranging from 1.4 to 3.1 nm. The results were found to be in good agreement wit h literature data and confirm the analytical potential of the applied technique. (C) 1997 Elsevier Science Ltd.