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1.
Adam F Vendeuvre C Bertoncini F Thiébaut D Espinat D Hennion MC 《Journal of chromatography. A》2008,1178(1-2):171-177
A new column association using comprehensive two-dimensional gas chromatography for the detailed molecular analysis of hydrocarbon mixtures is reported in this paper. In order to compare the impact of two different secondary columns, a novel column combination relying on a GC x 2GC system was used. This system is based on a non-polar first column (PONA) combined with both a permethylated beta-cyclodextrin (beta-Dex 120) stationary phase and a polysilphenylensiloxane (BPX 50) in the second dimension. Compared to BPX 50 stationary phase, the implementation of beta-cyclodextrin columns as the second dimension was found to improve the resolution between paraffins and naphthenes in the naphtha range but not in the middle distillate range. Attempts to improve the results and to understand the interaction mechanism remained unsuccessful. Therefore, the benefits of the beta-Dex 120-column are only demonstrated on heavy naphtha cut for the quantitation of hydrocarbons. 相似文献
2.
I. Azzouz J. Vial D. Thiébaut R. Haudebourg K. Danaie P. Sassiat J. Breviere 《Analytical and bioanalytical chemistry》2014,406(4):981-994
This review covers the recent development of stationary phases for chip-based gas chromatography (GC). Portable systems for rapid and reliable analysis are urgently needed. One way to achieve this is to miniaturize the entire analysis. Because the column is the central component of the GC system and determines the feasibility and quality of separation, this review focuses on stationary phases reported in the literature and their use in different fields during the last two decades, with emphasis on different methods for introducing the stationary phase into the GC column. 相似文献
3.
LetX be a complex manifold with finitely many ends such that each end is eitherq-concave or (n−q)-convex. If
, then we prove thatH
pn−q
(X) is Hausdorff for allp. This is not true in general if
(Rossi’s example withn=2 andq=1). If all ends areq-concave, then this is the classical Andreotti-Vesentini separation theorem (and holds also for
). Moreover the result was already known in the case when theq-concave ends can be ‘filled in’ (again also for
). To prove the result we first have to study Serre duality for the case of more general families of supports (instead of
the family of all closed sets and the family of all compact sets) which is the main part of the paper. At the end we give
an application to the extensibility of CR-forms of bidegree (p, q) from (n−q)-convex boundaries,
.
This research was partially supported by TMR Research Network ERBFMRXCT 98063. 相似文献
4.
Frédérick Adam Didier Thiébaut Fabrice Bertoncini Marion Courtiade Marie-Claire Hennion 《Journal of chromatography. A》2010,1217(8):1386-1394
This paper reports the conditions of online hyphenation of supercritical fluid chromatography (SFC) with twin comprehensive two-dimensional gas chromatography (twin-GC × GC) for detailed characterization of middle distillates; this is essential for a better understanding of reactions involved in refining processes. In this configuration, saturated and unsaturated compounds that have been fractionated by SFC are transferred on two different GC × GC columns sets (twin-GC × GC) placed in the same GC oven. Cryogenic focusing is used for transfer of fractions into the first dimension columns before simultaneous GC × GC analysis of both saturated and unsaturated fractions. The benefits of SFC–twin-GC × GC are demonstrated for the extended alkane, iso-alkane, alkene, naphthenes and aromatics analysis (so-called PIONA analysis) of diesel samples which can be achieved in one single injection. For that purpose, saturated and unsaturated compounds have been separated by SFC using a silver loaded silica column prior to GC × GC analysis. Alkenes and naphthenes are quantitatively recovered in the unsaturated and saturated fractions, respectively, allowing their identification in various diesel samples. Thus, resolution between each class of compounds is significantly improved compared to a single GC × GC run, and for the first time, an extended PIONA analysis of diesel samples is presented. 相似文献
5.
Vendeuvre C Bertoncini F Thiébaut D Martin M Hennion MC 《Journal of separation science》2005,28(11):1129-1136
Modeling the retention in comprehensive two-dimensional gas chromatography (GC x GC) was achieved using retention indices obtained in conventional GC. Predicted results were compared with experimental data obtained in the two-dimensional separation of a synthetic hydrocarbon mixture. This proved to be helpful in optimizing the operating conditions of GC x GC separation of a complex petroleum sample and in identifying chemical families. 相似文献
6.
Vial J Thiébaut D Marty F Guibal P Haudebourg R Nachef K Danaie K Bourlon B 《Journal of chromatography. A》2011,1218(21):3262-3266
Since the late 1970s, approaches have been proposed to replace conventional gas chromatography apparatus with silicon-based microfabricated separation systems. Performances are expected to be improved with miniaturization owing to the reduction of diffusion distances and better thermal management. However, one of the main challenges consists in the collective and reproducible fabrication of efficient microelectromechanical system (MEMS) gas chromatography (GC) columns. Indeed, usual coating processes or classical packing with particulate matters are not compatible with the requirements of collective MEMS production in clean room facilities. A new strategy based on the rerouting of conventional microfabrication techniques and widely used in electronics for metals and dielectrics deposition is presented. The originality lies in the sputtering techniques employed for the deposition of the stationary phase. The potential of these novel sputtered stationary phases is demonstrated with silica sputtering applied to the separation of light hydrocarbons and natural gases. If kinetic characteristics of the sputtered open tubular columns were acceptable with 2500 theoretical plates per meter, the limited retention and resolution of light hydrocarbons led us to consider semipacked sputtered columns with rectangular pillars allowing also significant reduction of typical diffusion distances. In that case separations were greatly improved because retention increased and efficiency was close to 5000 theoretical plates per meter. 相似文献
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Using functional analysis and a Friedrichs approximation lemma for first order differential operators, we derive a global
homotopy formula in large degrees for the tangential Cauchy-Riemann operator from local homotopy formulas without loss of
regularity. 相似文献