However, accurate measurement of molecular size distribution can only be obtained under conditions in which aggregation of the sulphated chains does not take place. This has been achieved by operating both column and eluent at high temperature and by adding iodide salts of non-gelling cations [e.g., Li+, Na+, N(CH3)4+, etc.] to the solvent, since these salts induce an ordered conformation without further aggregation (Hjerde et al., 1999 and Sworn et al., 1987).