20 (2014) Scientific papers, Series A
Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/75412
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Článekpeer-reviewedpublished Otevřený přístup Utilization of hydrosilated silica-based stationary phases for separation of antioxidants(University of Pardubice, 2014) Soukup, Jan; Janás, Petr; Jandera, PavelWe studied the influence of mobile phase composition on the retention of phenolic acids and flavonoid compounds on five different hydrosilated silica-based stationary phases in buffered aqueous acetonitrile. Cogent UDC cholesterolTM, Cogent bidentate C18TM and Cogent Phenyl hydrideTM columns show significant dual reversed-phase/normal-phase retention behaviour, while Cogent Diamond hydrideTM and Cogent Silica-CTM columns provide very low retention in the reversed-phase mode. The effect of the aqueous acetate buffer concentration on retention factors of phenolic acids and flavonoid compounds over the full mobile phase composition range, including both aqueous normal-phase (ANP) and reversed-phase (RP) mechanisms, can be described by a four-parameter equation for dual-retention mechanism. At increasing temperature, the retention factors and peak widths decrease in the aqueous normal-phase range. In agreement with van’t Hoff model, linear ln k versus 1/T plots were observed, showing a single retention mechanism. From among the stationary phases tested, Cogent UDC cholesterolTM column has high temperature stability (up to 100 °C) and provides the most selective and efficient separations of flavones in the ANP mode and Cogent Diamond hydrideTM is the most selective and effective for separation of phenolic acids.Článekpeer-reviewedpublished Otevřený přístup Modification reactions applicable to polymeric monolithic columns. A review(University of Pardubice, 2014) Currivan, Sinéad; Jandera, PavelOrganic monolithic columns can be prepared from co-polymerizations of functional monomer and a cross-linker, resulting in a desired surface functionality. They can also be prepared to form a generic polymer monolith, in which the functionality can be altered by using a number of post-polymerization modifications. The reactions used to convert surface functionality include reaction chemistry, thermal or photo-initiated polymerization reactions, or the addition of nano-architectures, such as nano-particles or nano-tubes. This review article aims to highlight the available options in the modification of polymeric monolithic columns prepared by thermal or UV initiated polymerizations.