ELECTROPHORETIC BEHAVIOR OF FULLY SULFONATED POLYSTYRENES IN CAPILLARIES FILLED WITH ENTANGLED POLYMER-SOLUTIONS

Very little work has been reported so far on the separation of synthet ic or industrial polyelectrolytes by CE. Following the pioneering work by Poll and Schure (Anal. Chem., 64 (1992) 896), a more extensive stu dy was undertaken on the separation of standard sodium polystyrenesulf onates (PSS), with molecular masses ranging between 16 and 990x10(3), in capillaries filled with entangled hydroxyethylcellulose (HEC, M-r 2 50x10(3)) or polyethyleneoxide (PEG, M-r 100x10(3)) solutions as sievi ng media. Both bare and polyethyleneglycol (PEG) coated silica capilla ries were successfully carried out for achieving the separation. As a consequence, the detection order was easily inverted. Nevertheless, PE G-coated capillaries should not be used in conjunction with chemically similar PEO solutions, owing to PSS-PEG interactions. In order to ana lyze the electrophoretic behaviour of PSS in these polymer solutions, viscosity measurements directly performed using the CE instrument enab led 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 pre sented in detail. The PSS migration regimes are also analyzed on the b asis of classical models (Ogston, modified Ogston, reptation, biased r eptation) that were initially established to account for DNA migration in permanent gels. The impact of PSS molecular masses and conformatio n and of network pore size is highlighted.