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- 2017 (13) (entfernen)
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- MALDI-TOF MS (4)
- MALDI (3)
- Polylactides (3)
- Ring-opening polymerization (3)
- Conductive carbon tape (2)
- Pollen (2)
- Sample pretreatment (2)
- Transesterification (2)
- Bewitterung (1)
- Blockcopolymer (1)
- Catalysts (1)
- Cationization (1)
- Controlled radical polymerization (1)
- Cyclopolymerization (1)
- Dispersity (1)
- Equilibration (1)
- Feuchte (1)
- Hybrid nanoparticles (1)
- Iron oxide nanoparticles (1)
- Irreversible polycondensation (1)
- Lactides (1)
- Laser-induced redox reactions (1)
- MALDI TOF MS (1)
- Mass spectrometry (1)
- Morphology (1)
- Nanoparticles separation asymetrical flow field flow fractionation (1)
- Nässe (1)
- Oligospiroketals (1)
- PCA (1)
- Polycaprolactone (1)
- Polyester (1)
- Polylactide (1)
- Polymer MALDI (1)
- Polymerization (1)
- Polystyrene (1)
- Polyurethan (1)
- Principal component analysis (1)
- Ring-expansion polymerization (1)
- Sn catalysts (1)
- Sulfobetaines (1)
- TPU (1)
- Target plate material (1)
- Tin catalysts (1)
- UV (1)
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.
The nucleophilic thiol–ene (thia-Michael) reaction between molecular rods bearing terminal thiols and bis-maleimides was investigated. The molecular rods have oligospiroketal (OSK) and oligospirothioketal (OSTK) backbones. Contrary to the expectations, cyclic oligomers were always obtained instead of linear rigid-rod polymers. Replacing the OS(T)K rods with a flexible chain yielded polymeric products, suggesting that the OS(T)K structure is responsible for the formation of cyclic products. The reason for the preferred formation of cyclic products is due to the presence of folded conformations, which have already been described for articulated rods.
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is often applied to assess the dispersity and the end groups of synthetic polymers through the addition of cationizing agents. Here weaddress how these cation adducts are formed using polystyrene (PS) as a model polymer. We analyzed PSby MALDI-MS with a 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile (DCTB) as the matrix and a range of trifluoroacetate (TFA) salts as cationizing agents on a range of different targetplate materials (copper, 1.4301 stainless steel, aluminum, Inconel 625, Ti90/Al6/V4 and chromium-, gold-and silver-plated stainless steel). It was found that on a stainless steel substrate the metal cations Al+,Li+, Na+, Cu+and Ag+formed polystyrene adducts, whereas K+, Cs+, Ba2+, Cr3+, Pd2+, In3+, or their lower oxidation states, did not. For the copper and silver substrates, PS and DCTB adduct formation with cations liberated from these target plate materials was observed upon addition of a cationizing agent, which indicates the occurrence of redox reactions between the added TFA salts and the target plate material. Judging from their standard electrode potentials, these redox reactions would not normally occur, i.e.,they require an additional energy input, strongly suggesting that the observed redox reactions are laser-induced. Furthermore, copper granules were found to successfully sequester PS from a tetrahydrofuran(THF) solution, consistent with the view complex formation with the copper target plate can take place prior to the MALDI-MS measurement.