Evaluation of Hungarian Wines for Resveratrol by Overpressured Layer Chromatography

A method, including solid phase extraction sample preparation, overpressured layer chromatographic separation and subsequent densitometric evaluation, was developed for measurement of total resveratrol (cis- and trans-isomers) content of wine. The amount of resveratrol was determined in wine samples from different winemaking regions of Hungary. The total resveratrol was high in Hungarian red wines (3.6–11 mg/L), and much lower in white ones (0.04–1.5 mg/L)

Nouvelles approches de la séparation de phénothiazines et de leurs dérivés en électrophorèse capillaire

International audienc

A Theoretical Investigation of the Potentialities of the Use of a Multidimensional Column in Chromatography

Two-dimensional column chromatography is a method which combines the advantages of column chromatography (constant, adjustable flow velocity, excellent efficiency, on-line detection) and two-dimensional thin-layer chromatography (successive developments in two perpendicular directions, using two different retention mechanisms). It is shown that by merely keeping constant the solvent flow velocity during the development of a thin-layer plate, a considerable increase in the spot capacity can be achieved, since plate length and particle size can be selected without any prejudicial influence on the solvent velocity which can be kept constant at the value considered as optimum by the analyst. Calculations show that two-dimensional column chromatography can generate peak capacities well in excess of 500, up to several thousands, and that the specifications for the equipment are not too stringent. A 10 × 10 cm column would be 1 mm thick, be well packed with 10-μm particles and be operated at a reduced velocity of 10. Such a packing could be expected to be very homogeneous (A = 0.7) and the reduced plate height would be 1.95. The expected spot capacity is 900, while the pressure drop for a compound with a diffusion constant D = 5 × 10-6, cm2/sec (linear velocity, u, = 0.05 cm/sec) and a solvent with viscosity 1 cP is only 5 atm (flow-rate 3 cm3/min). The sample spot should be about 1 mm in diameter or less. Equipment capable of these performances is under construction. Successful operation of this two-dimensional separation scheme, however, relies on the ability to find two chromatographic systems operating according to widely different mechanisms

New MEKC apprroachs to separate phenothiazines and their derivatives

International audienc

Nouvelles approches de la séparation de phénothiazines et de leurs dérivés en électrophorèse capillaire

International audienc

Optimization of St John's Wort flavonoid separation by reversed phase liquid chromatography on a silica-based monolithic column

International audienceAn optimization procedure for the separation of fJavonoids from St John's Wort by reversed- phase high-performance liquid chromatography on monolithic stationary phase is described. Three-component mobile phase systems are studied using experimental design methodology The starting experimental domain is a triangle, each vertexofwhich is a pure component. From preliminary isocratic experiments, truncations in the domain are performed leading to a quadrilateral shape working domain with no symmetry To cope with both separation and analysis time, desirability functions are used. Optimal conditions are finally given by binary systems and the four flavonoids are separated in less than seven minutes

A false transient approach to steady state solution of fluid flow through vascular constrictions

10.1007/BF00370040Computational Mechanics74269-277CMME