Nuclear magnetic resonance and high-performance liquid chromatographic evaluation of polymer-based stationary phases immobilized on silica.
Three poly(ethylene-co-acrylic) acid copolymers (-CH(2)CH(2)-)(x)[CH(2)CH(CO(2)H)-](y) with different chain lengths and mass fractions of acrylic acid were covalently immobilized as stationary phases on silica via two variants of spacer molecules (3-aminopropyltriethoxysilane and 3-glycidoxypropyltrimethoxysilane). Different mobilities of the alkyl chains in the stationary phases were observed using (13)C solid-state NMR spectroscopy. The stationary phases with more rigid trans-ordered alkyl chains had better selectivity for geometric beta-carotene and xanthophyll isomers (provitamin A derivatives). Also, all the separations of the analytes were affected by polar interactions with the chromatographic sorbent. This was further proved by separating more polar cis/trans retinoic acid isomers (vitamin A derivatives). (13)C high-resolution/magic-angle spinning (HR/MAS) NMR measurements of the chromatographic sorbents suspended in the mobile phase confirmed a dependence of molecular shape recognition ability on alkyl chain conformation.
Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076 Tuebingen, Germany.
Christoph
C
Meyer
Urban
U
Skogsberg
Norbert
N
Welsch
Klaus
K
Albert
D000180:Acrylic Resins / Q000138:chemical synthesis / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D011095:Polyethylenes / Q000138:chemical synthesis / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*; D013237:Stereoisomerism; D013499:Surface Properties
D000180:Acrylic Resins; D011095:Polyethylenes; D012822:Silicon Dioxide; C083316:(polyethylene-acrylic acid) copolymer