Filtern
Erscheinungsjahr
Dokumenttyp
- Vortrag (12)
- Zeitschriftenartikel (9)
- Beitrag zu einem Sammelband (9)
- Beitrag zu einem Tagungsband (8)
- Posterpräsentation (7)
- Buchkapitel (2)
Sprache
- Englisch (47) (entfernen)
Referierte Publikation
- nein (47) (entfernen)
Schlagworte
- MALDI-TOF MS (6)
- MALDI (4)
- Mass spectrometry (4)
- Polylactide (4)
- Ionization (2)
- MALDI TOF MS (2)
- Pollen (2)
- Polymers (2)
- Ring-opening polymerization (2)
- Transesterification (2)
- Adhesion promoting interlayers (1)
- Biobased (1)
- Biobased polymers (1)
- Carbon capture (1)
- Catalyst (1)
- Catalysts (1)
- Chemical conversion of functional groups (1)
- Chromatography (1)
- Climate change (1)
- Conductive carbon tape (1)
- Copolymers (1)
- Coupling techniques (1)
- Crystalinity (1)
- Cyclic (1)
- Depollution (1)
- Desorption (1)
- ESI (1)
- ESI-TOF MS (1)
- Electrospray ionization (1)
- Equilibration (1)
- Field flow fractionation (1)
- HPLC (1)
- Hyperbranched polyesters (1)
- ICP-MS (1)
- Imaging techniques (1)
- Isotope dilution analysis (1)
- Linear (1)
- Liquid adsorption chromatography (1)
- Lubricant (1)
- MALDI-TOF Mass Spectrometry (1)
- MALDI-ToF MS (1)
- Matrix-assisted laser desorption/ionization (1)
- Metal-polymer interactions (1)
- Metal-polymer systems (1)
- Micro manufacturing (1)
- Multiphysics simulations (1)
- Multivariate statistics (1)
- Nanoparticles separation asymetrical flow field flow fractionation (1)
- Oxygen low-pressure plasma treatment of polymers (1)
- Peel strength (1)
- Plasma modification (1)
- Plasma polymers with functional groups (1)
- Poly(lactide) (1)
- Polyethylene (1)
- Polyglycolide (1)
- Polylactides (1)
- Polymer (1)
- Polymer chromatography (1)
- Polymer mass spectrometry (1)
- Polymere (1)
- Polymerisation (1)
- Polypropylene (1)
- Principal component analysis (1)
- Ring-expansion polymerization (1)
- Sample pretreatment (1)
- Silver nanoparticles (1)
- Spacers (1)
- Surface analysis (1)
- Tandem MS (1)
- Time of flight (1)
- Tin acetates (1)
- Toxicology (1)
- WMRIF (1)
- r.f. pulsed plasma (1)
Organisationseinheit der BAM
- 6 Materialchemie (9)
- 6.3 Strukturanalytik (9)
Eingeladener Vortrag
- nein (12)
The performance of a miniaturized channel for the separation of polymer and metal nanoparticles (NP) using Asymmetrical Flow Field-Flow Fractionation (AF4) was investigated and compared with a conventional AF4 system. To develop standard separation methods, experimental parameters like cross flow, gradient profile and injection time were varied and optimized.
Corresponding chromatographic parameters were calculated and compared. Our results indicate that the chromatographic resolution in the miniaturized channel is lower, whereas significantly shorter analyses time and less solvent consumption were obtained. Moreover, the limit of detection (LOD) and limit of quantification (LOQ) obtained from hyphenation with a UV-detector are obviously lower than in a conventional channel, which makes the miniaturized channel interesting for trace analysis.
Poly(l-lactide)s are synthesized and annealed at 120 °C and changes of the molecular weight distribution (MWD) are monitored by matrix-assited laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. For example, benzyl alcohol+SnOct2 causes equilibration of odd- and even-numbered chains and the final goal of the transesterification is the most probable distribution. The underlying intermolecular transesterification is even observed at 100 and 80 °C in the solid state. However, cyclic tin mercaptide catalysts transform the initial most probable distribution into a MWD with maxima, which display a conspicuous fine structure due to a preferential crystallization of certain ring sizes. The optimum ring sizes for the crystallization are provided by ring-ring equilibration. The gradual formation of a special morphology shifts the melting temperature to values up to 187 °C. Annealing of commercial poly(l-lactide) with a cyclic tin catalyst also yields a distribution of mass peaks with a maximum showing the characteristic fine structure.
Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) is a well-implemented analytical technique for the investigation of complex biological samples. In MS, the sample preparation strategy is decisive for the success of the measurements. Here, sample preparation processes and target materials for the investigation of different pollen grains are compared. A reduced and optimized sample preparation process prior to MALDI-TOF measurement is presented using conductive carbon tape as target. The application of conductive tape yields in enhanced absolute signal intensities and mass spectral pattern information, which leads to a clear separation in subsequent pattern analysis. The results will be used to improve the taxonomic differentiation and identification, and might be useful for the development of a simple routine method to identify pollen based on mass spectrometry.
Glycolide was polymerized in bulk by means of four different ROPPOC catalysts: tin(II) 2-ethylhexanoate (SnOct2), dibutyltin bis(pentafluoro-phenoxide) (BuSnOPF),zinc biscaproate (ZnCap), and zinc bis(pentafluoro-phenyl sulfide) (ZnSPF). The temperature was varied between 110 and 180°C and the time between 3 h and 7 days. For the few polyglycolides (PGAs) that were soluble extremely high molecular masses were obtained. The MALDI TOF mass spectra had all a low signal-to-noise ration and displayed the peaks of cyclic PGAs with a“saw-tooth pattern ”indicating formation of extended-ring crystallites in the mass range below m/z 2500. The shape of DSC curves varied considerably with catalyst and reaction conditions, whereas the long-distance values measured by SAXS were small and varied little with the polymeriza-tion conditions.
Ring-expansion polymerizations (REPs) catalyzed by two cyclic tin catalysts (2-stanna-1.3-dioxa-4,5,6,7-dibenzazepine [SnBiph] and
2,2-dibutyl-2-stanna-1,3-dithiolane [DSTL]) are performed at 140 °C in bulk.
Small amounts (4 vol%) of chlorobenzene or other solvents are added to
facilitate transesterification reactions (ring–ring equilibration) in the solid poly(l-lactide)s. In the mass range up to m/z 13 000 crystalline PLAs displaying a so-called saw-tooth pattern in the MALDI-TOF mass spectra are obtained indicating the formation of extended-ring crystals. The characteristics of extended-ring crystallites and folded-ring crystallites are discussed. Furthermore, extremely high melting temperatures (Tm’s up to 201.2 °C) and melting enthalpies (𝚫Hm’s up to 106 J g−1)) are found confirming that 𝚫Hm max, the 𝚫Hm of a perfect crystal, is around or above 115 J g−1 in contrast to literature data.
A reversed phase high performance liquid chromatography coupled to an inductively coupled plasma mass spectrometer (HPLC-ICP-MS) approach in combination with isotope dilution analysis (IDA) for the separation and parallel quantification of nanostructured and ionic silver (Ag) is presented. The main focus of this work was the determination of the ionic Ag concentration. For a sufficient stabilization of the ions without dissolving the nanoparticles (NPs), the eluent had to be initially optimized. The determined Ag ion concentration was in a good agreement with results obtained using ultrafiltration. Further, the mechanism of the NP separation in the HPLC column was investigated. Typical size exclusion effects were found by comparing results from columns with different pore sizes. Since the recovery rates decreased with increasing Ag NP size and large Ag NPs did not elute from the column, additional interactions of the particles with the stationary phase were assumed. Our results reveal that the presented method is not only applicable to Ag NPs, but also to gold and polystyrene NPs. Finally, IDA-HPLC-ICP-MS experiments in single particle mode were performed to determine the particle cut-off size. The comparison with conventional spICP-MS experiments resulted in a similar diameter and particle size distribution.