Flow field-flow fractionation of high-molecular-mass polyacrylamide

The fractionation of high-molecular-mass polyacrylamide in aqueous solution s by size-exclusion chromatography is complicated by concerns over adsorpti on and shear degradation. The coupling of flow field-flow fractionation (fl ow FFF), multi-angle laser light scattering (MALLS) detection and a concent ration-sensitive detector provided absolute measurement of molecular mass d istributions in a low shear environment. Critical to the success of the met hod was the careful selection of the carrier solution. A number of commerci al polyacrylamide standards with mean molecular masses in the range 0.35 to 9.00.10(6) were studied. The breadth of the distributions indicated the pr esence of entangled or agglomerated polymer. Diffusion coefficients calcula ted from both light scattering and flow FFF retention were comparable, as w ell as being consistent with extrapolations from literature values for lowe r-molecular-mass polyacrylamides. (C) 1999 Elsevier Science B.V. All rights reserved.