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Peter J. Schoenmakers - One of the best experts on this subject based on the ideXlab platform.
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Recent applications of chemometrics in one- and Two-Dimensional Chromatography.
Journal of separation science, 2020Co-Authors: Tijmen S. Bos, Wouter C. Knol, Stef R.a. Molenaar, Leon E. Niezen, Peter J. Schoenmakers, Govert W. Somsen, Bob W.j. PirokAbstract:The proliferation of increasingly more sophisticated analytical separation systems, often incorporating increasingly more powerful detection techniques, such as high-resolution mass spectrometry, causes an urgent need for highly efficient data-analysis and optimization strategies. This is especially true for comprehensive Two-Dimensional Chromatography applied to the separation of very complex samples. In this contribution, the requirement for chemometric tools is explained and the latest developments in approaches for (pre-)processing and analyzing data arising from one- and Two-Dimensional Chromatography systems are reviewed. The final part of this review focuses on the application of chemometrics for method development and optimization.
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Construction and initial evaluation of an apparatus for spatial comprehensive Two-Dimensional liquid-phase separations
Analytica chimica acta, 2011Co-Authors: Dominique J.d. Vanhoutte, Sebastiaan Eeltink, Wim Th. Kok, Peter J. SchoenmakersAbstract:Spatial comprehensive Two-Dimensional Chromatography is discussed as a potentially alternative to the conventional column-based approach. In "spatial" separations each analyte ends up in a specific location, rather than being eluted at a specific time. Ultimately, higher peak-capacity-production rates (peak capacity per unit time) may be attained by spatial two- and three-dimensional separations. While low-pressure planar Chromatography is well developed, the high-pressure equivalent is still in its infancy. We discuss the requirements for a device for high-pressure spatial Two-Dimensional Chromatography and we describe a possible design. A prototype instrument has been constructed in-house. The preparation of a polymer monolithic separation body and a valve configuration that allows manual sample injection are described. Initial tests of this study included the investigation of the homogeneity of the monolith and the flow profile through the separation body. Furthermore, in order to evaluate the current chromatographic performance of the device, a mixture of dyes was separated in one dimension within 30 s.
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Transfer-volume effects in Two-Dimensional Chromatography: Adsorption-phenomena in second-dimension size-exclusion Chromatography
Journal of chromatography. A, 2010Co-Authors: Eva Reingruber, Jeroen J. Jansen, Wolfgang Buchberger, Peter J. SchoenmakersAbstract:Gradient-elution LC × LC is a valuable technique for the characterization of complex biological samples as well as for synthetic polymers. Breakthrough and viscous fingering may yield misleading information on the sample characteristics or deteriorate separation. In LC × SEC another phenomenon may jeopardize the separation. If the analytes adsorb on the SEC column under the injection-plug conditions, peak splitting may occur. In LC × LC the effluent from the first column is the sample solvent for the analytes injected into the second dimension. If a gradient-elution LC × SEC setup is used (i.e. if reversed-phase gradient-elution LC is coupled to organic SEC and if normal-phase gradient-elution LC is coupled to SEC with a polar solvent), the percentage of weak solvent may be significant, especially at short analysis times. In this case adsorption in the first-dimension-effluent zone on the second-dimension SEC column can become an issue and two peaks--the first eluting in size-exclusion mode and the second undergoing adsorption--can be obtained. The work presented in this paper documents peak splitting in LC × SEC of polymers. The adsorption of the polymer on the size-exclusion column was proven in one-dimensional isocratic runs. The observed effects were modeled and visualized through simulation. Studies on the influence of the transfer volume were carried out. Keeping the transfer volume as small as possible helped to minimize peak splitting due to adsorption.
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Development of a resolution metric for comprehensive Two-Dimensional Chromatography
Journal of chromatography. A, 2007Co-Authors: S.w.m. Peters, Gabriel Vivó-truyols, Philip J. Marriott, Peter J. SchoenmakersAbstract:A new resolution metric for Two-Dimensional Chromatography is proposed and tested. This resolution measurement is based on the concept of the (one-dimensional) valley-to-peak ratio, which has been adapted and modified for Two-Dimensional Chromatography. Two questions are considered related to the computation of the resolution of a given (Two-Dimensional) peak. First, the concept of peak neighbourhood is revised, since it changes drastically from one- to Two-Dimensional Chromatography. In a chromatogram resulting from a Two-Dimensional analysis, one peak may be surrounded by more than two neighbouring peaks. However, the neighbouring peaks can be remote from the peak or some interfering peaks may be in between. In these cases, it is not meaningful to compute the resolution between them. A method is proposed to determine whether a resolution measurement between two Two-Dimensional peaks is reasonable. Second, a measurement of the valley-to-peak ratio in Two-Dimensional Chromatography is proposed. The measurement is based on the concept of the saddle point (which is defined for Two-Dimensional surface plots). A study of the correlation of the valley-to-peak ratio with the error obtained for quantification is presented. The new metric can be used as an estimator of the quantification errors. Also, valley-to-peak ratios can be calculated for one or more target peak(s) to estimate the separation quality of the entire chromatogram. This makes the proposed measurement suitable for optimisation purposes. Although the algorithm was developed for GC x GC, preliminary studies suggested that its application to other Two-Dimensional separation methods (e.g. LC x LC) should only require minor modification (if any).
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Development of an algorithm for peak detection in comprehensive Two-Dimensional Chromatography.
Journal of chromatography. A, 2006Co-Authors: Sonja Peters, Philip J. Marriott, Gabriel Vivó-truyols, Peter J. SchoenmakersAbstract:A method for peak detection in Two-Dimensional Chromatography is presented. The algorithm applies first the methods developed for peak detection in one-dimensional Chromatography to detect peaks in one dimension. In a second step, a decision tree is applied to decide which one-dimensional peaks are originated from the same compound and have to be 'merged' into one Two-Dimensional peak. To this end, different features of the peaks (second-dimension peak regions and second-dimension retention times) are compared and different criteria (common peak regions, retention time differences, unimodality in the first dimension) are applied. Different options can be used, depending on the nature of the data. The user controls this decision tree by establishing several options and "switches". The algorithm was tested with GCxGC chromatograms obtained for a commercial air-freshener sample, detecting and merging the modulated peaks belonging to the same compound. Recommendations for the set of options and switches are given. A utility that calculates and sums peak areas from merged peaks is added to facilitate automated quantification. Although the algorithm was developed for GCxGC, its application to comprehensive Two-Dimensional liquid Chromatography (LCxLC) data should at most require minor modifications.
Harald Pasch - One of the best experts on this subject based on the ideXlab platform.
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two dimensional Chromatography of complex polymers 8 separation of fatty alcohol ethoxylates simultaneously by end group and chain length
Journal of Separation Science, 2010Co-Authors: Jacquesantoine Raust, Adele Bruell, Pritish Sinha, Wolf Hiller, Harald PaschAbstract:A comprehensive Two-Dimensional liquid Chromatography system was developed to precisely describe the molecular heterogeneity of fatty alcohol ethoxylates. The end-group functionality was analyzed by gradient HPLC while ethylene oxide oligomer distributions were characterized by liquid adsorption Chromatography. A baseline separation of all functionality fractions irrespective of the ethylene oxide oligomer chain length was achieved on nonpolar X-Terra® C18 with a methanol–water gradient, whereas an isocratic flow of isopropanol–water on a polar Chromolith® Si column gave a separation according to the oligomer chain length without interference of the end-group distribution. The combination of these two methods to conduct online Two-Dimensional liquid Chromatography experiments resulted in a comprehensive Two-Dimensional picture on the molecular heterogeneity of the sample.
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two dimensional Chromatography of complex polymers 6 method development for meth acrylate based copolymers
Journal of Chromatography A, 2008Co-Authors: Jacquesantoine Raust, Adele Brull, Claudine Moire, Celine Farcet, Harald PaschAbstract:The free-radical copolymerisation of various acrylates and methacrylates resulting in complex copolymers for cosmetic applications were investigated using different chromatographic techniques including HPLC and on-line coupled Two-Dimensional (2D) liquid Chromatography. The complete separation of all polymerisation products was achieved by gradient HPLC. A computated optimisation procedure, using the Polymer Chromatographic Model allowed us to design a step mobile phase gradient to improve resolution of homopolymer chromatographic separation. By combining gradient HPLC and SEC (Size Exclusion Chromatography) in a fully automated Two-Dimensional Chromatography setup, the complex distributions of chemical composition and molar mass could be simultaneously described and fingerprinted.
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Two-Dimensional Chromatography of complex polymers, 5 Separation of blends of styrene-butadiene rubber and butyl rubber
e-Polymers, 2003Co-Authors: Lars-christian Heinz, A. Siewing, Harald PaschAbstract:Abstract Separation of blends of styrene-butadiene rubber and butyl rubber was accomplished by gradient HPLC. Using a polar stationary phase and chloroformcyclohexane as eluent, the blends were separated with regard to chemical composition, irrespective of the molar masses of the components. The exact chemical structure of the blend components was analysed by coupling the chromatographic separation to FTIR detection. FTIR spectra of the components reveal information on styrene and butadiene contents and the conformation of the butadiene units (1,2-, 1,4-cis and 1,4-trans units). Complete separation of the blends with respect to chemical composition and molar mass was achieved by Two-Dimensional liquid Chromatography. Combining gradient HPLC and size exclusion Chromatography in a fully automated 2D Chromatography set-up, the complex distributions of chemical composition and molar mass were fingerprinted simultaneously.
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Two‐dimensional Chromatography of complex polymers. IV. Analysis of the grafting reaction of methyl methacrylate onto polybutadiene
Journal of Polymer Science Part A: Polymer Chemistry, 2003Co-Authors: A. Siewing, B. Lahn, D. Braun, Harald PaschAbstract:The grafting reaction of methyl methacrylate onto polybutadiene (PB) was investigated with different chromatographic techniques, including high-performance liquid Chromatography (HPLC) and online coupled Two-Dimensional liquid Chromatography. As a result of the grafting reaction, a complex mixture of nongrafted PB, the graft copolymer PB-g-PMMA [where PMMA is poly(methyl methacrylate)], and the PMMA homopolymer was formed. The complete separation of all the products of the grafting reaction was achieved with gradient HPLC. By the combination of gradient HPLC and size exclusion Chromatography in a fully automated Two-Dimensional Chromatography setup, the complex distributions of the chemical composition and molar mass were fingerprinted simultaneously. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3143–3148, 2003
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Use of gradient, critical and Two-Dimensional Chromatography in the analysis of styrene- and methyl methacrylate-grafted epoxidized natural rubber.
Journal of Applied Polymer Science, 2003Co-Authors: Sven M. Graef, André J. P. Van Zyl, Ronald D. Sanderson, Bert Klumperman, Harald PaschAbstract:The growing number of heterogeneous polymeric species that are being synthesized places increasing demands on existing analytical techniques. Although size-exclusion Chromatography (SEC) has established itself as a powerful analytical tool, it has its limits when complex polymers, e.g., graft copolymers, must be analyzed. In this case, complementary techniques such as gradient HPLC and liquid Chromatography at critical conditions (LCCC) are more favorable. The present study describes the synthesis and analysis of methyl methacrylate- and styrene-grafted epoxidized natural rubber by different chromatographic techniques. The grafting efficiency was evaluated by gradient HPLC under normal and reversed phase conditions. Methyl methacrylate-grafted ENR50 was further analyzed by LCCC, where separation of the rubber and grafted rubber occurred according to chemical composition but was independent of the molar mass of the methyl methacrylate homopolymers. This was followed by the combination of LCCC and SEC, where separation was achieved in two dimensions. Relevant deductions were made of both the chemical composition distribution and the molar mass distribution of the functional groups of methyl methacrylate-grafted ENR50. © 2003 Wiley Periodicals, Inc.
Simona T. Popovici - One of the best experts on this subject based on the ideXlab platform.
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Two-Dimensional Chromatography as a tool for studying band broadening in size-exclusion Chromatography
Journal of Separation Science, 2005Co-Authors: Simona T. Popovici, Aschwin Van Der Horst, Peter J. SchoenmakersAbstract:Comprehensive 2-D size-exclusion Chromatography (SEC×SEC) has been realized. SEC×SEC is not a useful technique for characterizing complex polymers. However, it is potentially an elegant tool to study band-broadening phenomena. If narrow fractions can be collected from the first dimension, the band broadening in the second dimension is only due to chromatographic dispersion. This would allow a clear distinction to be made between chromatographic band broadening (column and extra-column) and SEC selectivity (band broadening due to sample polydispersity). In comparison with MALDI-MS, SEC×SEC allows the study of polymers across a much broader molar-mass range.
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Two-Dimensional Chromatography as a tool for studying band broadening in size-exclusion Chromatography : New Achievements in Chromatography
Journal of Separation Science, 2005Co-Authors: Simona T. Popovici, Aschwin Van Der Horst, Peter J. SchoenmakersAbstract:Comprehensive 2-D size-exclusion Chromatography (SEC x SEC) has been realized. SEC x SEC is not a useful technique for characterizing complex polymers. However, it is potentially an elegant tool to study band-broadening phenomena. If narrow fractions can be collected from the first dimension, the band broadening in the second dimension is only due to chromatographic dispersion. This would allow a clear distinction to be made between chromatographic band broadening (column and extra-column) and SEC selectivity (band broadening due to sample polydispersity). In comparison with MALDI-MS, SEC x SEC allows the study of polymers across a much broader molar-mass range.
Vladimir N. Sidelnikov - One of the best experts on this subject based on the ideXlab platform.
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Separation of phenol-containing pyrolysis products using comprehensive Two-Dimensional Chromatography with columns based on pyridinium ionic liquids.
Journal of separation science, 2016Co-Authors: Mikhail V. Shashkov, Vladimir N. SidelnikovAbstract:We describe the application of columns with highly polar stationary liquid phases based on pyridinium ionic liquids for the Two-Dimensional Chromatography separation of bio-oil and product of coal pyrolysis. By using inverse combination columns-a first ionic liquid column and a second nonpolar column-good separation results have been obtained. In the analysis of coal pyrolysis products, the suggested approach provides a much better resolution between components in comparison with a less polar first-dimension column (based on polyethylene glycol). A good selectivity for the peaks of phenols is observed, and the group of phenols is well detached and separated from the group of diaromatics. A good separation picture was obtained also for bio-oil, the groups of phenols and guaiacol derivatives are distinguished with good resolution of substances within each group.
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Separation of Phenol-Containing Pyrolysis Products Using Comprehensive Two-Dimensional Chromatography with Columns Based on Pyridinium Ionic Liquids
Journal of Analytical & Bioanalytical Techniques, 2016Co-Authors: Mikhail V. Shashkov, Vladimir N. SidelnikovAbstract:The work describes the application of columns with high-polar stationary liquid phases based on pyridinium ionic liquids for GC × GC separation of bio-oil and product of coal pyrolysis. By using inverse combination columns- the first ionic liquid column, the second is HP-5 the good separation results have been obtained. In the analysis of coal pyrolysis products, the suggested approach provides a much better resolution between components in comparison with a less polar first-dimension column (ZB-WAX). The good selectivity for peaks of phenols is observed, and the group of phenols is well detached and separated from the group of diaromatics. For bio-oil also good separation picture was obtained, the groups of phenols and guaiacol derivatives are distinguished with good resolution of substances within each group.
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Thermostable columns based on ionic liquids for the analysis of hydrocarbon mixtures by Two-Dimensional Chromatography
Protection of Metals and Physical Chemistry of Surfaces, 2015Co-Authors: M. V. Shashkov, Vladimir N. SidelnikovAbstract:We studied thermostable capillary columns with stationary phases based on ionic liquids (IL) as the second columns in Two-Dimensional Chromatography. The use of dicationic imidazolium and pyridinium ILs was shown to provide higher working temperatures compared to conventional polar phases (up to 280–300°C), which allows qualitative separations of high-boiling hydrocarbon mixtures, for example, catalytic gas oil with bp up to 400°C. It was shown also that a higher selectivity of separation between the groups of aromatic hydrocarbons compared to the commonly used polyethylene glycol-based polar phase can be achieved on such columns.
Aschwin Van Der Horst - One of the best experts on this subject based on the ideXlab platform.
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Two-Dimensional Chromatography as a tool for studying band broadening in size-exclusion Chromatography
Journal of Separation Science, 2005Co-Authors: Simona T. Popovici, Aschwin Van Der Horst, Peter J. SchoenmakersAbstract:Comprehensive 2-D size-exclusion Chromatography (SEC×SEC) has been realized. SEC×SEC is not a useful technique for characterizing complex polymers. However, it is potentially an elegant tool to study band-broadening phenomena. If narrow fractions can be collected from the first dimension, the band broadening in the second dimension is only due to chromatographic dispersion. This would allow a clear distinction to be made between chromatographic band broadening (column and extra-column) and SEC selectivity (band broadening due to sample polydispersity). In comparison with MALDI-MS, SEC×SEC allows the study of polymers across a much broader molar-mass range.
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Two-Dimensional Chromatography as a tool for studying band broadening in size-exclusion Chromatography : New Achievements in Chromatography
Journal of Separation Science, 2005Co-Authors: Simona T. Popovici, Aschwin Van Der Horst, Peter J. SchoenmakersAbstract:Comprehensive 2-D size-exclusion Chromatography (SEC x SEC) has been realized. SEC x SEC is not a useful technique for characterizing complex polymers. However, it is potentially an elegant tool to study band-broadening phenomena. If narrow fractions can be collected from the first dimension, the band broadening in the second dimension is only due to chromatographic dispersion. This would allow a clear distinction to be made between chromatographic band broadening (column and extra-column) and SEC selectivity (band broadening due to sample polydispersity). In comparison with MALDI-MS, SEC x SEC allows the study of polymers across a much broader molar-mass range.
