Models of SEC elution curves for binary and multi‐component polymers

BACKGROUND: Frequently, the unimodal shape of size‐exclusion chromatography (SEC) elution curves is taken as evidence that the polymer sample being analysed contains no minority components in significant quantities. The legitimacy of this assumption, however, has never been checked systematically. RESULTS: An algorithm for the simulation of SEC elution curves of multi‐component polymer systems has been developed. Using the algorithm, the shapes of the overall SEC curves with a wide range of parameters describing binary systems were generated and scanned. The crucial parameters determining the shape of the elution curves are the ratio of the molecular weights of the components, the breadth of the molecular weight distribution of the components, the mass fractions of the components and the band broadening. CONCLUSION: A detailed inspection of the curves shows that the identification of the presence of minority components in such systems from the shapes of the elution curves is more difficult then generally assumed. The absence of peak irregularities, such as minima or inflection points, widely used as a proof of absence of minority components, is a highly unreliable criterion. Copyright © 2008 Society of Chemical Industry