Separation Sciences
Prof. dr. P. Sandra
| Postdoctoral researchers | |
| Beatriz Bicalho |
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| PhD students | |
| Maarten De Beer Nathalie De Coensel Isabelle François Vivienne Malanchin Bram Miserez Els Van Hoeck |
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| Other staff | |
| Marc Schelfaut | |
| Research topics | |
In our lab, attention is being paid to the most important fields of instrumental analytical chemistry. We have numerous interesting research projects carried out utilizing modern separation techniques, such as:
We specifically focus on hyphenation techniques, i.e. coupling the separation techniques to state-of-the-art spectroscopic detectors, such as:
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| Gas Chromatography | |
Currently two major projects in GC are carried out in our group: 1. Analysis of Volatiles Signaling Plant Stress An interesting topic in modern plant research comprises the determination of plants' responses to harmful external factors, such as wounding, insect feeding, pathogen attack, etc. Through the analysis of plant headspaces, under normal and stressed conditions, these volatile signal molecules are identified. In a later stage the genes interfering in the compound's biosynthesis are determined with as final goal the production of transgenic plants producing for example their own pesticide. The main objective of our work involves the development of a fully automated system for the analysis of volatile biogenic emissions. Via a multi-switching system we can sample, in a semi-continuous fashion, the volatile emissions emanating from a stressed and a reference plant. The system uses both automated static sampling (SPME) and automated dynamic sampling (sorption/thermodesorption) for high sensitivity analyses. After sampling trapped volatiles are analyzed using GC-MS. Research period: People involved: 2. The development of a continuous monitoring system for the determination of dioxines or precursors in gaseous samples During the last years, the analysis of dioxins has received a lot of attention in Belgium because of the closure of some incinerators that emitted concentrations higher than 0.1 ng/m 3 and the dioxin or better polychlorbiphenyl (PCB's) scandal of our food products. Whereas the food pollution can be considered as an exceptional and occasional situation, the daily emission of dioxins in the atmosphere is a more serious problem. The analytical technique used nowadays for dioxin analysis, namely high resolution gas chromatography combined with high resolution mass spectrometry (HRGC-HRMS) is very expensive (price 20.10 6 BEF) and requires highly specialised technicians to produce accurate data. Only few laboratories can invest in such equipment. This means that the capacity for dioxin analysis is rather small. Optimisation of incinerator parameters to minimize dioxin emission needs, however, frequent measurements. On the other hand, looking in detail in the dioxin method, it is clear that recent developments especially in capillary GC have not been implemented yet. It is the aim of this work to construct and evaluate on-line monitoring systems that allow to measuring dioxins directly or indirectly via precursors. High resolution gas chromatography combined with low resolution negative chemical ionisation MS (HRGC-LRNCIMS) should offer an alternative to high resolution mass spectrometry (HRGC-MS) for the direct determination of dioxins. The selectivity can be guaranteed by implementing polar biscyanopropylsiloxane capillary columns with small internal diameters (100 µm i.d.). The method translation software and the concept of retention time locking will be implemented as well. The sensitivity compared to normal CGC can be improved by using large volume injection via a programmed temperature vaporisation (PTV) injector operating in the solvent vent mode. In a second part, precursors in air samples that show a mathematical correlation with dioxins and furans will be traced. We have evidence that some of the chlorobenzenes, present in 1000-fold higher concentration, can be used to predict dioxin concentrations. If this is confirmed, an on-line monitor system consisting of sorptive extraction, thermal desorption, capillary gas chromatography and electron capture detection will be constructed. Sorptive extraction can be performed either in the break-through or equilibrium mode. The latter offers higher sensitivity. If precursors cannot be found, an on-line system consisting of sorptive extraction, thermal desorption, capillary gas chromatography and low resolution negative chemical ionisation MS will be evaluated. The performance of the developed methods will be checked by comparison with data, obtained in parallel, with the official method and then validated. It is the aim, to implement such an on-line system in an incinerator installation. Research period: People involved:
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| Liquid Chromatography: | |
Current major projects in LC are: Project of ... Research period: People involved:
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| Capillary Electrophoresis & Capillary Electrochromatography : | |
Several interesting projects employing CE & CEC are: 1. Exploratory investigation of the polyphenolic content of cannabinoid free Cannabis species for the identification of oestrogenic and other medicinal properties.
Research period: People involved: 2. Capillary Electrophoresis of Polysaccharides To achieve the separation and detection of high distribution of polysaccharides, to develop the method of identification of the polysaccharides, capillary electrophoresis(CE) coupled with laser induced fluorescence(LIF) is the promising method to analysis polysaccharides, which need very high separation effiency and detection sensitivity due to their high distrbution of polymers. Research period: People involved: 3. Open-Tubular Capillary Electrochromatography (OT-CEC) : Theory and Practice The aim of this Ph.D. dissertation is to evaluate existing techniques and to develop new techniques for the reproducible manufacturing of open tubular CEC columns. The latter is the key aspect of this work because CEC will never be accepted if its robustness does not equals that of CGC and LC. Open tubular columns will be used for the combination of CEC with MS, and this mainly to screen combinatorial libraries using affinity based seperations, and for the combination of CEC with ICPMS and this for metal speciation and to study protein-metal interactions. Research period: People involved: 4. Affinity Capillary Electrophoresis and Electrochromatography coupled with Mass Spectrometry and the applicability for the screening of combinatorial libraries. The aim of the project is the development of a fast and straightforward screening and identification technique for the analysis of solution based combinatorial libraries. State-of-the-art electrodriven separation techniques like affinity capillary electrophoresis and affinity capillary electrochromatography are therefore compared with pressure driven separations like high performance liquid affinity chromatography. Hyphenation of the different techniques with mass spectrometry is also major and complex issue. Optimisation of the methods is done using a model study which is based on the well known interactions of the macrocyclic antibiotic vancomycin with specific oligopeptides. Hence peptide libraries corresponding to this interactions are synthesised on solid phase and used in different affinity experiments. Eventually the best technique is tested with a combinatorial library of the tetrapodal type which is screened on a synthetic peptide which mimics the a crucial peptide sequence of the HIV-I. Research period: approx. 4 years People involved:
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| Supercritical Fluid Chromatography: | |
The research project involving SFC coupled to NMR is a PhD study of Koen Desmet for a period of 4 to 5 years: Untill now the identification of unknown compounds was a real struggle. Isolating, collecting, purifying and enriching the compound of interest was a time consuming task. In search of a technique who would simplify this all, researchers made the logical choice to combine the technique that provides the most structural information , namely nuclear magnetic resonance spectroscopy (NMR), with the present techniques. Broadening the field of application and optimising the coupling between liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) with NMR will be the main purpose of this Ph. D study.
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| Mass Spectrometric Detectors: | |
We have an wide variety of mass spectroscopic instrumentation, such as:
People in charge:
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| Theses | |
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| Publications 2001 | |
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| Other links | |
| Pfizer: www.pfizer.com
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