title: Ion-exclusion controlled size-exclusion chromatography of methacrylic acid-methyl methacrylate copolymers.
abstract: Controlled ion-exclusion allows compensation of hydrophobic adsorption in size-exclusion chromatography of negatively charged methacrylic acid-methyl methacrylate (Eudragit) polymers using methanol as a mobile phase. Properly selected low-ionic-strength conditions below 5 mM LiCl provide correct separation in the size-exclusion mode. Possible disturbing effects, mainly related to light scattering, under low-salt conditions are discussed and shown to be negligible if on-line concentration-light scattering detection is used. The absence of these disturbances is checked by a comparison of experiments performed in methanol containing 1.25 mM and 2.5 mM LiCl. Molecular mass averages and distributions identical within the experimental error are obtained.
authors.affiliation: Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague.
authors.forename: B
authors.initials: B
authors.lastname: Porsch
authors.forename: I
authors.initials: I
authors.lastname: Hillang
authors.forename: A
authors.initials: A
authors.lastname: Karlsson
authors.forename: L O
authors.initials: LO
authors.lastname: Sundelöf
mesh_terms: D002850:Chromatography, Gel / Q000379:methods*; D007477:Ions; D008689:Methacrylates / Q000032:analysis*; D020366:Methylmethacrylate / Q000032:analysis*; D011108:Polymers
chemical_list: D007477:Ions; D008689:Methacrylates; D011108:Polymers; D020366:Methylmethacrylate; C008384:methacrylic acid