Matrix-assisted laser desorption distribution studies

In a separate study, a protocol for Matrix-assisted laser desorption-ionization (MALDI) imaging mass spectrometry (IMS) has been proposed.18 This IMS technique provides a new approach to visualize spatial distribution of thousands of molecular species, including peptides, proteins, and their metabolites in two- or three-dimensional levels. This approach may also provide a straightforward method of determining the tissue distribution of multiple peptides or proteins in a quantitative manner.18 Chu et al.19 reported a nondestructive molecular extraction method to obtain proteins from a single FFPE or frozen tissue section, without destroying the tissue morphology, such... 

Among them, MS has become a valuable tool in studying polymer structure, composition, molecular weight distribution (MWD), and other important physical quantities [2-5]. Different MS techniques have been employed, with different degree of applicability and success, in providing comprehensive quantitative information on the sample analyzed. Traditional approaches such as ionization techniques [2, 5-10] or modern ones such as matrix-assisted laser desorption ionization (MALDl) MS [4, 11-13] are used to obtain structural and compositional information. 

Of these MSI techniques, matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) is a soft ionization technique which does not produce fragments, or, at least, produces fewer ions fragments. In addition, its high sensitivity, accuracy, and spatial resolution made it suitable to measure the composition of compounds or biomacromolecules. So it can determine the distribution of peptides, proteins, or other chemicals and so on within thin slices of biological samples. Robinson et al. used MALDI-MS to measure the localization of water-soluble carbohydrates in wheat stems in situ and their method (Figure 10.26) may be useful for researchers of metallomics to carry out the study between metal or non metal and organism. 

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. 

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