MALDI mass spectroscopy

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 low volatility of ILs makes them useful as solvents working under high vacuum, and together with their more amorphous solid analogs they are convenient in matrix-assisted laser-desorption/ ionization-mass spectroscopy (MALDI-MS) analysis.103104... 

Matrix assisted laser desorption ionization-time of flight mass spectroscopy (MALDI-TOF MS) has proven to be a powerful tool for analysis of many biopolymers, such as proteins, oligonucleotides, and polysaccharides. Recently, it has been used to characterize many synthetic polymers [174]. Another... 

In 1981 Barber and Liu and coworkers [1,2] independently introduced the concept of employing matrix-assisted desorption/ionization where the absorption of the matrix is chosen to coincide with the wavelength of the employed laser to assist in the volatilization of materials. In 1988 Tanaka, Hillenkamp and coworkers [3,4] employed the laser as the energy source giving birth to matrix-assisted laser/ desorption mass spectroscopy (MALDI MS). 

Kassalainen and Williams [135] coupled thermal field flow fractionation (ThFFF) and matrix-assisted laser desorption/ionisation time-of-flight mass spectroscopy (MALDI-ToF-MS) to yield a powerful combination of techniques for the analysis of polydisperse PS. ThFFF high selectivity and sensitivity to chemical composition were used to separate polydisperse polymers and polymer mixtures into the narrow polydispersity and homogeneous chemical composition fractions essential for MAT.DT-ToF-MS analyses. On the other hand, because it is possible to measure directly using MALDI-ToF-MS, it alleviates the need for polymer standards for ThFFF. Kassalainen and Williams [135] address the coupling of ThFFF and MALDI-ToF-MS and identify compatibility issues. Optimum conditions were determined and developed to maximise the capabilities of the combined technique. Depending on the polymer and the method of matrix-assisted laser desorption/ionisation (MALDI) sample deposition, fractions from 1-10 ThFFF runs were combined for MALDI-ToF-MS analysis. Binary solvents are used to enhance ThFFF retention and resolution of low (<15 kDa) polymers, and methods developed to allow routine MALDI-ToF-MS analyses of PS polymers up to 575 kDa. Overall, the compatibility of the two techniques was extended from several kilodaltons to several hundred kDa. Polymer... 

Dwyer [7] combined SEC and matrix assisted laser desorption ionisation - mass spectroscopy (MALDI-MS) to provide an insight into the structure and MWD of polymers. He showed that there are a number of factors that can influence results. 

Montaudo and co-workers [10] studied the distribution of polymethyl acrylate-polybutylene adipate. Matrix assisted laser desorption ionisation - time of flight mass spectroscopy (MALDI) allows desorption and ionisation of very large molecules, even in complex mixtures. However, molar mass estimates provided by MALDI-ToE for synthetic polymers agree with the values obtained by conventional techniques only in the case of samples with a narrow molar mass distribution (MMD). However, when polydisperse polymer samples are fractionated by analytical SEC, they yield fractions with very narrow distributions which, when analysed by MALDI, are found to give mass spectra with molar mass values in excellent agreement with those obtained by conventional techniques. 

In this context, dialdehyde la (5 mg, 0.017 mmol), sarcosine (14 mg, 0.157 mmol) and five-fold excess of Ceo (60 mg, 0.083 mmol) dissolved in 10 ml of o-dichlorobenzene (o-DCB) heated at 130 °C for 90 min. After a typical work up procedure, the reaction mixture is purified by recycling HPLC on a preparative Buckyprep Cosmosil column (250 X 20 mm, toluene eluent, lOml/min flow rate) to furnish bis-fullerene derivative 3 in 32 % yield. The bis-fullerene 3 shows moderate solubility, thus allowed us to record and NMR spectra (Supp. Info., Fig. SI) corroborating the depicted structure in Scheme 1. The attenuated-total-reflectance infra-red (ATR-IR) spectrum of 3 demonstrates the characteristic stretching vibrations of the C-H (2803-3030cm" ) as well as the characteristic absorptions for fullerenes (Supp. Info., Fig. S2). Matrix-assisted-laser-desorption time-of-flight mass-spectroscopy (MALDI-TOF-MS), in the negative ionization mode and with the aid of trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile shows the molecu-... 

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