title: Zirconia based monoliths used in hydrophilic-interaction chromatography for original selectivity of xanthines.
abstract: Monolithic capillary columns based on zirconia were prepared directly from zirconium alkoxide. They were also prepared coating a classical silica based monolithic column with zirconium butoxide. Using the gradual evolution of the theophylline/caffeine separation factor, it was found that successive zirconia coatings produced the progressive fading of surface silanols replaced by Zr-OH groups. The behavior of a silica monolith coated four times with zirconium butoxide was very similar to that of a pure zirconia monolith. The dramatic change in xanthine separation factor observed with zirconia stationary phases and the theophylline and caffeine probe solutes was used to develop a complete separation of xanthines on zirconia stationary phase in less than 6 min. The three dimethylxanthine isomers, theophylline, theobromine and paraxanthine, are very difficult to separate in RPLC with classical C18 stationary phases. The three isomers were easily separated in HILIC mode on a zirconia based stationary phase.
authors.affiliation: Laboratoire des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon1, CNRS, Bâtiment Curien, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex, France. randon@univ-lyon1.fr
authors.forename: Jérôme
authors.initials: J
authors.lastname: Randon
authors.forename: Samuel
authors.initials: S
authors.lastname: Huguet
authors.forename: Claire
authors.initials: C
authors.lastname: Demesmay
authors.forename: Alain
authors.initials: A
authors.lastname: Berthod
mesh_terms: D002110:Caffeine / Q000302:isolation & purification; D002853:Chromatography, Liquid / Q000295:instrumentation*; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D009994:Osmolar Concentration; D012822:Silicon Dioxide / Q000737:chemistry; D013806:Theophylline / Q000302:isolation & purification; D014867:Water / Q000737:chemistry; D014970:Xanthines / Q000737:chemistry / Q000302:isolation & purification*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D014970:Xanthines; D014867:Water; D002110:Caffeine; D012822:Silicon Dioxide; D013806:Theophylline; D015040:Zirconium; C028541:zirconium oxide