Separations of anionic and cationic synthetic polyelectrolytes by capillary gel electrophoresis

The separation of anionic [poly(styrene-4-sulfonates)] and cationic [poly(2-vinylpyridines)] synthetic polyelectrolytes in CE is described. Dextrans have been used as sieving media, because they combine excellent UV translucence and good water solubility. The poly(styrene-4-sulfonates) as strong polyelectrolytes can be separated under alkaline as well as acidic conditions. The separation under acidic conditions is possible for low acid high molecular masses even in uncoated fused-silica capillaries, Systems without electroosmotic flow have to be used in alkaline medium. For the cationic polymers surface modification of the capillary is obligatory to avoid wall adsorption of the solutes. All analytes exhibit similar migration properties to DNA in sieving media. The mass-selectivity range can be adjusted by the chain length (molecular mass) of the dextran. The resolution of the standards can be optimized via dextran concentration in the buffer. In contrast to CE separations of DNA and small molecules increasing band broadening here means better monitoring of solute polydispersity. (C) 1998 Elsevier Science B.V.