MALDI-TOF spectroscopy

Using MALDI-TOF spectroscopy, 2-propoxybenzyhdene was foimd to be the end group in all of the polymers prepared by the action of Ru(CF3COO)2 (l,3-dimesityl-4,5-dihydroimidazl-2-yhdene)(CH-(2-(2-PrO)-C6H4))),indicat-ing the absence of any chain transfer reactions. The polymerization of chiral... 

F. Altmann, Vienna) performed by matrix-assisted laser desorption ionization time of flight (MALDI-TOF) spectroscopy. Top N-glycan analysis of wild-type. Bottom N-glycan analysis of a transgenic moss strain lacking plant-specific sugar residues. 

Pharmaceutical develop- MALDI-TOF spectroscopy Typically blinded studies and matched patient groups. 

Roger, S., Spickermann, J., Morrison, D. L., Dziezok, R, and Rader, H. J., Aggregates of Shape Persistent Macrocyclic Amphiphiles Detected by MALDI-TOF Spectroscopy, Macromolecules, 30, 3110, 1997. 

The chain length of poly(MOT) films was determined by MALDI-TOF spectroscopy, because these polymers are soluble in usual organic solvents. Th consist mainly of MOT hexamer (Scheme 3). 

Quirk and co-workers [25] evaluated the amount of chain transfer to monomer during the alkyl lithium initiated polymerisation of 1,3 cyclohexadiene. This was achieved by characterisation of the products from ethylene oxide termination. The products were separated by SEC, thin layer chromatography, proton magnetic resonance spectroscopy and MALDI-ToF spectroscopy. 

The molecular weights and molecular weight distributions (MWD) of phenolic oligomers have been evaluated using gel permeation chromatography (GPC),23,24 NMR spectroscopy,25 vapor pressure osmometry (VPO),26 intrinsic viscosity,27 and more recently matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).28... 

Considering these situations, the observation of molecular weights, particularly by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MASS), is essential [33]. The operation is simple and enables us to observe the molecular ion peaks of CPOs with molecular weights exceeding 10,000. The quahty of the measurement is strongly dependent on the choice of the matrix. Therefore, the search for the best matrix for each CPO should be pursued. 

The effects of the feed ratio in the lipase CA-catalyzed polymerization of adipic acid and 1,6-hexanediol were examined by using NMR and MALDI-TOF mass spectroscopies. NMR analysis showed that the hydroxyl terminated product was preferentially formed at the early stage of the polymerization in the stoichiometric substrates. As the reaction proceeded, the carboxyl-terminated product was mainly formed. Even in the use of an excess of the dicarboxylic acid monomer, the hydroxy-terminated polymer was predominantly formed at the early reaction stage, which is a specific polymerization behavior due to the unique enzyme catalysis. 

Besides MALDI-TOF mass spectroscopy, by which the monodispersity of all the above described dendritic compounds was proven, H-NMR spectroscopy was again found to be a most informative characterization method, since most signals from the hydrogens at the different stereogenic centers have unique shifts. The resonances from analogous protons of the peripheral, interior and central units were always well separated and shifted towards lower field on going from outside to inside (for detailed discussion see our recent full paper [90]). 

The combination of a number of these techniques often provides complementary information on end group structure and hence the mechanism of polymerisation. The synergy between MALDI-TOF MS and NMR spectroscopy is particularly powerful, with MS/MS providing additional information where necessary. MALDI-TOF MS provides information on individual oligomers,... 

Evidence for a competing disproportionation mechanism (see Figure 1) for the termination of chain ends is provided by the combined presence of the peaks from 4 and 5 in the MALDI-TOF mass spectrum of this PMMA polymer (see Figure 6) [10]. Confirmation of the presence of the unsaturated and saturated chain ends, arising from disproportionation, was obtained by means of and 13C NMR spectroscopy, respectively [11]. 

A combination of NMR spectroscopy and MALDI-TOF MS is commonly employed in our laboratory for the characterisation of PPG polymers. Analysis of di-hydroxyl end-capped PPG (18) is initially described. The [H NMR spectrum [54] can be used to confirm the backbone structure of the polymer, as can be seen in Figure 22 (a and b are from the backbone of the polymer, with c from the methyl side chains). Peaks of low intensity, downfield of those from the backbone of the polymer, in the HNMR spectrum may be used to identify and quantify the allyl functionality in the polymer [55]. These resonances (d, e and f) are... 

A range of tetradentate Schiff-base ligands have also been employed to prepare discrete aluminum alkoxides. The most widely studied system is the unsubstituted parent system (256), which initiates the controlled ROP of rac-LA at 70 °C in toluene. The polymerization displays certain features characteristic of a living process (e.g., narrow Mw/M ), but is only well behaved to approximately 60-70% conversion thereafter transesterification causes the polydispersity to broaden.788 MALDI-TOF mass spectroscopy has been used to show that even at low conversions the polymer chains contain both even and odd numbers of lactic acid repeat units, implying that transesterification occurs in parallel with polymerization in this system.789... 

Polymer 163 (and similar alternating copolymers of 9,9-dioctylfluorene and oxadiazole <2002MM3474>) with blue-light-emitting activity were synthesized by the Suzuki coupling reaction and studied by GPC, MALDI-TOF MS, LJV spectroscopy, and several other techniques <2002ANC6252>. 

From the analytical point of view, reactions were efficiendy monitored using a combination of FTIR (Fourier transform infrared), TLC (thin-layer chromatography), and MALDI-TOF mass spectroscopy analysis of crudes resulting from the cleavage of small resin samples. 

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