title: Adamantyl-group containing mixed-mode acrylamide-based continuous beds for capillary electrochromatography. Part I: study of a synthesis procedure including solubilization of N-adamantyl-acrylamide via complex formation with a water-soluble cyclodextrin.
abstract: A new synthesis procedure for highly crosslinked macroporous amphiphilic N-adamantyl-functionalized mixed-mode acrylamide-based monolithic stationary phases for capillary electrochromatography (CEC) is investigated employing solubilization of the hydrophobic monomer by complexation with a cyclodextrin. N-(1-adamantyl)acrylamide is synthesized and characterized as a hydrophobic monomer forming a water soluble-inclusion complex with statistically methylated-β-cyclodextrin. The stoichiometry, the complex formation constant and the spatial arrangement of the formed complex are determined. Mixed-mode monolithic stationary phases are synthesized by in situ free radical copolymerization of cyclodextrin-solubilized N-adamantyl acrylamide, a water soluble crosslinker (piperazinediacrylamide), a hydrophilic monomer (methacrylamide), and a negatively charged monomer (vinylsulfonic acid) in aqueous medium in bind silane-pretreated fused silica capillaries. The synthesized monolithic stationary phases are amphiphilic and can be employed in the reversed- and in the normal-phase mode (depending on the composition of the mobile phase), which is demonstrated with polar and non-polar analytes. Observations made with polar analytes and polar mobile phase can only be explained by a mixed-mode retention mechanism. The influence of the total monomer concentration (%T) on the chromatographic properties, the electroosmotic mobility, and on the specific permeability is investigated. With a homologues series of alkylphenones it is confirmed that the hydrophobicity (methylene selectivity) of the stationary phase increases with increasing mass fraction of N-(1-adamantyl)acrylamide in the synthesis mixture.
authors.affiliation: University of Marburg, Department of Chemistry, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
authors.forename: Ayat Allah
authors.initials: AA
authors.lastname: Al-Massaedh
authors.forename: Ute
authors.initials: U
authors.lastname: Pyell
mesh_terms: D020106:Acrylamide / Q000737:chemistry*; D000218:Adamantane / Q000031:analogs & derivatives* / Q000737:chemistry; D053801:Capillary Electrochromatography / Q000379:methods*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D009930:Organic Chemicals / Q000737:chemistry / Q000302:isolation & purification; D012044:Regression Analysis; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D009930:Organic Chemicals; D047392:beta-Cyclodextrins; D020106:Acrylamide; D000218:Adamantane