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

Construction of mixed-level supersaturated designs and comparison of their performance: Application to a gas chromatographic method

International audienceA supersaturated design is a design for which there are fewer runs than effects to be estimated. Although two-level supersaturated designs are becoming increasingly popular, mixed-level designs are scarcely used. Mixed-level designs are needed when the response is based on a polynomial response surface model or in situations where factors are nominal variables (with more than two modalities). The aim of this study is to explore the construction of mixed-level supersaturated designs and to evaluate their performance from the analysis of peppermint oil using a gas chromatographic method as application. This experimental setup requires the study of seven factors at two levels and five factors at three levels. Different building methods are tested from asymmetric or symmetric supersaturated designs. The mixed-level supersaturated designs obtained are compared from the point of view of a priori criteria with the aim of evaluating which criteria are better suited to judge the quality and fitness for purpose of these experimental designs. Finally, the results of the supersaturated designs are compared to the complete classical design. (C) 2011 Elsevier B.V. All rights reserved