 | November 1, 2009
By:Inge Dirinck, Isabelle Van Leuven, Patrick Dirinck
Mass spectrometry-based electronic nose technology (MS-nose technology) is a fast hyphenated technique for digital odour characterization of food and beverage products.
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May 1, 2009
By:Hans-Gerd Janssen, Filippo Bedani
Two-dimensional liquid chromatography (2D-LC) allows analysts to deal with complex samples that either cannot be adequately separated by one-dimensional liquid chromatography (1D-LC) or require excessively long analysis times. Peptide mixtures, whose characterization is relevant in many areas (e.g., proteomics, food analysis, pharmaceutical, life sciences), are a clear example of such complexity. An overview of the most used 2D-LC modes of operation is presented and several examples of their use for the separation of peptide mixtures are described.
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February 1, 2009
By:Michael P. Balogh
Part 2 of this three-part series focuses on comparing operation and performance of the most well known mass spectrometers.
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January 1, 2009
By:Philip J. Marriott, Weeraya Khummueng
The interpretation of comprehensive two-dimensional gas chromatography (GC×GC) based on the modulation ratio (MR) concept encompasses method implementation, ideas on quantitative measurement and how modulation phase affects GC×GC.
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November 1, 2008
By:Robert A. Shellie
Differential flow modulation is an inexpensive way to perform GC×GC separations which has been attracting growing attention recently. Differential flow modulation uses high carrier gas flow rates in the second dimension column so it is widely thought that this rules out direct coupling with mass spectrometry. However direct coupled GC×GC-QPMS using differential flow modulation is reported here for the first time using an unmodified mass spectrometer comprising a dual inlet turbomolecular pump and fast scanning quadrupole mass analyser. The suitability of the approach for characterization of essential oils is demonstrated.
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November 1, 2007
By:Luc Nagels, Dr Hugo Bohets, Joseph Everaert, Bert Vissers, Justyna Sekula, Dr Marcus Brewster, Dr Koen Vanhoutte, Dr Nico Vervoort, Dr Karl Peeters, Kamilla Sadowska, Dominica Kozlowska, Dr Maria Eugenia Mongé
Potentiometry is a new detection method for liquid chromatography (LC) and capillary electrophoresis (CE). The principle behind this method is familiar to chromatographers because the signals depend on the partitioning tendency of analytes over the sensor coating and the eluent. This partitioning provokes a change in the surface potential and the detection of these changes can be classified as "potentiometric". A conversion algorithm is needed to convert the generated signals to concentration-related tracings (chromatograms).
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September 1, 2007
By:Erwin R. Kaal, Mitsuhiro Kurano, Margit Gei˛ler, Peter Schoemakers, Hans-Gerd Jannssen
Size-exclusion chromatography (SEC) and pyrolysis-gas chromatography (Py-GC) are commonly used to characterize copolymers. SEC is a powerful method to determine the molecular-weight distribution of polymers whereas Py-GC provides valuable information on their chemical composition. The combination of these two techniques could yield combined size and composition information for copolymers or polymer mixtures. A fully automated system was constructed to perform these two-dimensional (2D) characterizations. Several examples of the use of this new technique to comprehensively characterize polymers are described.
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