Résumé
Very little work has been reported so far on the separation of synthetic or industrial polyelectrolytes by CE. Following the pioneering work by Poli and Schure (Anal. Chem., 64 (1992) 896), a more extensive study was undertaken on the separation of standard sodium polystyrenesulfonates (PSS), with molecular masses ranging between 16 and 990×103, in capillaries filled with entangled hydroxyethylcellulose (HEC, Mr 250×103) or polyethyleneoxide (PEO, Mr 100×103) solutions as sieving media. Both bare and polyethyleneglycol (PEG) coated silica capillaries were successfully carried out for achieving the separation. As a consequence, the detection order was easily inverted. Nevertheless, PEG-coated capillaries should not be used in conjunction with chemically similar PEO solutions, owing to PSS–PEG interactions. In order to analyze the electrophoretic behaviour of PSS in these polymer solutions, viscosity measurements directly performed using the CE instrument enabled us to estimate some characteristic polymer parameters such as the radii of gyration, monomer dimensions, entanglement thresholds as well as average pore sizes of the separating network. The influence of the nature and concentration of the separating polymer, the nature of the buffer counter-ion, the ionic strength and the field strength are presented in detail. The PSS migration regimes are also analyzed on the basis of classical models (Ogston, modified Ogston, reptation, biased reptation) that were initially established to account for DNA migration in permanent gels. The impact of PSS molecular masses and conformation and of network pore size is highlighted.