Time filter

Source Type

Mönchengladbach, Germany

Peroni D.,University of Amsterdam | Sampat A.A.S.,University of Amsterdam | van Egmond W.,NLISIS | de Koning S.,European Technical Center | And 4 more authors.
Journal of Chromatography A | Year: 2013

Comprehensive two-dimensional gas chromatography (GC×GC) suffers from the impossibility to operate both dimensions at their optimum carrier gas velocity at the same time due to the different inner diameters of the columns typically employed. The use of multiple parallel capillary columns in the second dimension (GC×multi-GC) is studied as a means to achieve simultaneous optimum-velocity operation. A programme written in Microsoft Excel® was developed to calculate the efficiency of the two dimensions in GC×multi-GC for different numbers of columns in the second dimension. With the aid of this programme the appropriate number of columns was selected. Columns with maximum repeatability were specifically manufactured to grand suitable performance, i.e. to avoid band broadening effects caused by inter-column variations. 1D-GC experiments were carried out on the columns separately and combined in parallel. The performance of the parallel column set was consistent with that of the individual columns, with over 9100plates generated (approximately 10,000plates/m). A GC×multi-GC set-up was successfully installed. Model experiments proved the possibility to operate both dimensions at their optimum linear velocity simultaneously. The suitability of the novel second dimension column format to perform multidimensional separations was also shown for a number of selected applications. © 2013 Elsevier B.V.

Beckett M.A.,Bangor University | Horton P.N.,University of Southampton | Hursthouse M.B.,University of Southampton | Timmis J.L.,Bangor University | Varma K.S.,European Technical Center
Collection of Czechoslovak Chemical Communications | Year: 2010

[C6H5CH2NH3][B 5O6(OH)4] was obtained as colourless crystals in high yield from a MeOH/H2O (1:1) solution of benzylamine and boric acid (1:5). A single-crystal X-ray study confirmed that the solid-state structure was comprised of a supramolecular H-bonded pentaborate anion lattice, templated by the benzylammonium cations which occupy positions within the lattice cavities. Each pentaborate anion formed 4 H-bonds to 4 neighbouring pentaborate anions at α,α,α,β acceptor sites. Additionally, each cation H-bonds to 3 pentaborate anions. Crystals were monoclinic, P21/c, with a = 9.3511(2) Å, b = 14.5157(4) Å, c = 10.4670(2) Å, β = 90.778(2)°, T = 120 K, V = 1420.64(6) Å3, and Z = 4. TGA/DSC analysis showed that [C 6H5CH2NH3][B5O 6(OH)4] thermally decomposed in air at 800 °C to 2.5B2O3, via a low-temperature (200-250 °C) dehydration step to a condensed pentaborate. © 2010 Institute of Organic Chemistry and Biochemistry.

Peroni D.,University of Amsterdam | Vanhoutte D.,University of Amsterdam | Vilaplana F.,University of Amsterdam | Schoenmakers P.,University of Amsterdam | And 3 more authors.
Analytica Chimica Acta | Year: 2012

Hydrophobic macroporous polymer monoliths are shown to be interesting materials for the construction of "selective solvent gates" With the appropriate surface chemistry and porous properties the monoliths can be made permeable only for apolar organic solvents and not for water. Different poly(butyl methacrylate-co-ethylene dimethacrylate) (BMA-EDMA) and poly(styrene-co-divinylbenzene) (PS-DVB) monoliths prepared with tailored chemistries and porosities were evaluated for this purpose. After extensive characterization, the PS-DVB monoliths were selected due to their higher hydrophobicity and their more suitable flow characteristics. BMA-EDMA monoliths are preferred for mid-polarity solvents such as ethyl acetate, for which they provide efficient separation from water. Breakthrough experiments confirmed that the pressures necessary to generate flow of organic solvents through PS-DVB monoliths were substantially lower than for water. A phase separator was constructed using the monoliths as the flow selector. This device was successfully coupled on-line with a chip-based continuous liquid-liquid-extraction (LLE) system with segmented flow. Efficient separation of different solvents was obtained across a wide range of flow rates (0.5-4.0mLmin -1) and aqueous-to-organic flow ratios (β=1-10). Good robustness and long life-time were also confirmed. The suitability of the device to perform simple, cheap, and reliable phase separation in a continuous LLE system prior to gas-chromatographic analysis was proven for some selected real-life applications. © 2012 Elsevier B.V.

West M.,West X ray Solutions | Flower M.,European Technical Center | Jones S.,Glass technology services LTD | Jamieson S.,Bureau of Analysed Samples Ltd
Glass Technology: European Journal of Glass Science and Technology Part A | Year: 2014

Part 2 of this guide provides the glass-maker and analyst with practical advice and methodology for the chemical analysis of glass-making limestones and dolomites. XRF and ICP-OES instrumental techniques as well as conventional wet chemistry methods are described to satisfy arange of laboratory need and budgets.

Beckett M.A.,Bangor University | Horton P.N.,University of Southampton | Hursthouse M.B.,University of Southampton | Timmis J.L.,Bangor University | Varma K.S.,European Technical Center
Dalton Transactions | Year: 2012

The synthesis and characterization of a series of cyclo-alkylammonium pentaborate salts {[cyclo-C nH 2n-1NR 3][B 5O 6(OH) 4] (R = H, n = 3, 5-7 (1-4); R = Me, n = 6 (5))} are reported. Compounds 1, 2 and 5 have been further characterized by single-crystal XRD studies. Attempted recrystallization of 3 and 4 yielded small crops of the unexpected heptaborate salts, [cyclo-C 6H 11NH 3] 2[B 7O 9(OH) 5]·3H 2O·B(OH) 3 (6) and [cyclo-C 7H 13NH 3] 2[B 7O 9(OH) 5]·2H 2O·2B(OH) 3 (7) which were also characterized crystallographically. All compounds show extensive supramolecular H-bonded anionic lattices templated by the cations. H-bond interactions are described in detail. TGA-DSC analysis of the pentaborates 1-5 showed that they thermally decomposed in air at 800 °C to 2.5B 2O 3, in a 2 step process involving dehydration (<250 °C) and oxidative decomposition (250-600 °C). BET analysis of materials derived from the pentaborates had internal porosities of <1 m 2 g -1. © 2012 The Royal Society of Chemistry.

Discover hidden collaborations