Determination of the molecular mass distribution of synthetic polymers by size-exclusion electrochromatography

The performance of size-exclusion electrochromatography (SEEC) for the mass distribution analysis of synthetic polymers was studied and compared to co nventional, pressure-driven size-exclusion chromatography (SEC). Electroosm otic flow control, within-day, day-to-day and column-to-column repeatabilit y were determined for SEEC with respect to retention and separation efficie ncy. It was shown that by using the retention ratio instead of the migratio n time, the precision of the mass distribution calculations is sufficiently high, and that similar distributions were obtained for a sample analyzed b y pressure-driven SEC and by SEEC. Furthermore, hexafluoroisopropanol was d emonstrated to be a new and potent solvent for SEEC. It was used for the se paration of narrow poly methylmethacrylate standards and several commercial ly important polymers such as polycarbonate, polycaprolactam and poly(ethyl ene terephthalate), using UV detection in the deep UV region (195-230 nm). (C) 2001 Elsevier Science BV All rights reserved.