6533b826fe1ef96bd1284f44
RESEARCH PRODUCT
Apparent and Real Distribution in GPC (Experiments with PMMA Samples)
K. C. BergerG. V. Schulzsubject
ViscosityChemistryElutionDispersityGeneral EngineeringAnalytical chemistryRange (statistics)Molar mass distributionFunction (mathematics)Standard deviationVolumetric flow ratedescription
Abstract Molecular weight distribution curves obtained by GPC are broadened if concentration and flow rate are fixed in the usual range. Therefore, the apparent nonuniformity U app of the samples is larger than the real non-uniformity U = (Mw/Mn) −1. For a number of fractionated and unfractionated samples of polymethyl methacrylate we determined M n and M w by osmotic, light-scattering, and viscosity measurements. Thus, the real value of U can be compared to U app obtained by GPC at different concentrations and flow rates, υ. The excess nonuniformity U exc is evaluated as function of concentration c, polydispersity, molecular weight, and flow rate. For c = 0 and υ = 0, U exc is not far from zero. For standard conditions one certain value of the excess standard deviation of the elution volume allow calculation of U exc for narrow and broader distributions and the obtaining of nearly correct values for the real nonuniformity U.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1971-04-01 | Separation Science |