SIZE-BASED SEPARATION OF POLYELECTROLYTES BY CAPILLARY ZONE ELECTROPHORESIS - MIGRATION REGIMES AND SELECTIVITY OF POLY(STYRENESULPHONATES)IN SOLUTIONS OF DERIVATIZED CELLULOSE

The migration regimes and the separation selectivity of linear poly(st yrenesulfonates) (PSS) were investigated in solutions of linear polyme ric hydroxyethylcellulose (HEC). Variable parameters were the number o f PSS monomer units (in the range of 25-6520), HEC concentration (belo w and above the entanglement threshold), molecular mass of HEC (betwee n 35900 and 438000 Da) and electric field strength (from 190 to 1140 V /cm). Besides those regimes which are known for migration of polyelect rolytes in physical networks (Ogston sieving, reptation without and wi th orientation), the observed separation below the entanglement thresh old indicates an effect of solute-chain interactions similar to that o bserved for the separation of double-stranded DNA. From the dependence of the separation selectivity on HEC concentration and molecular weig ht it was found that both parameters increase the separation. The sele ctivity of the solutions of higher concentrated low molecular HEC was compared to lower concentrated high molecular HEC, which has a similar bulk viscosity, and therefore obeys comparable peak dispersion due to thermal broadening. At high field strengths (preferably used in capil lary electrophoresis) the former gave better separation only for short er PSS molecules. For separation of longer PSS molecules, only high mo lecular HEC is applicable due to the deformation of the low molecular matrix by large analyte molecules.