Electrospray ionization MALDI mass characterization

Selva and coworkers - reported on their experiences to apply various mass spectrometric techniques to the analysis of -carotene and carotenoids and their adducts formed in aqueous solution. El mass spectrometry and field desorption (FD) mass spectrometry were applied to aqueous mixtures of -carotene and /J-cyclodextrin, and the polyene was found to be detectable . Tandem mass spectrometry can be applied to identify fi-carotenone as a minor component in complex carotenoid mixtures. EI/MIKE spectrometry of the molecular ion m/z 600) was used in this case . A previous study was focused on the characterization of. vecw-carotcnoids using EI/MIKE and CID spectrometiy . The more recent ionization methods, viz. MALDI and its variant working without a matrix, laser desorption/ionization (EDI), as well as electrospray ionization (ESI) mass spectrometry, have also been applied to this topic. MALDI and LDI mass spectrometry were used to analyse mixtures of -carotene and y-cyclodextrin in aqueous solution. Adduct ions were not observed using these mctbods. ... 

Alhazmi,A., Giguere, M.S., Dube, M., Mayer, P.M. (2006) A comparison of electrospray-ionization and matrix-assisted laser desoption/ionization (MALDI) mass spectrometry with NMR spectroscopy for the characterization of synthetic copolymers. Eur. J. Mass Spectrom., 12,301-310. 

Three techniques have been mainly utilized to characterize gold clusters, namely mass spectroscopy, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and extended X-ray absorption fine structure spectroscopy (EXAFS). For unsupported gold clusters, electrospray ionization (ESI) mass spectrometry and matrix-assisted laser desorption ionization (MALDI) mass... 

Mass spectrometry is an emerging technology and now a core resource in all areas of viral research [1,2]. It is becoming a fundamental tool for work in areas such as protein characterization [3-6], structural virology [7-12], drug discovery [12,13], and clinical chemistry [14]. Most of the increased interest in this technique has been due to the development of matrix-assisted laser desorp-tion/ionization [15] (MALDI) and electrospray ionization (ESI) [16], which are highly sensitive and soft ionization techniques. 

Until 1988, the mass spectrometric analysis of peptides and proteins was difficult. Some results were achieved using (continuous-flow) fast-atom bombardment (FAB) and Cf plasma desorption. The major breakthrough in the characterization of proteins by mass spectrometry (MS) is due to the introduction of matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) in 1988. Currently, peptides and proteins form the compound class most intensively studied by MS. This is primarily due to the prominent role ESI-MS and MALDI-MS play in the field of proteomics. 

MS, especially in combination with advanced separation techniques, is one of the most powerful and versatile techniques for the structural analysis of bacterial glycomes. Modern mass spectral ionization techniques such as electrospray (ESI) and matrix-assisted laser desorption/ionization (MALDI) provide detection limits in the high atto- to low femto-mole range for the identification of peptides and complex carbohydrates. Structural characterization of these trace level components can be achieved using tandem MS. This provides a number of specific scanning functions such as product, precursor ion, and constant neutral loss scanning to... 

Electrospray ionization and MALDI represent major advances in the application of mass spectrometry to analysis of biomolecules. Although in many cases the two techniques are able to provide the same information, quite frequently they are complementary. For a variety of reasons, some samples are more successfully analyzed by MALDI and other by ESI. Thus, it is highly beneficial to have access to both types of instrument for characterization of synthetic peptides. In ESI-MS, the samples are introduced in solution at flow rates from less than 1 tL/min up to 1 mL/min, depending on the design of the ESI interface. Pure samples and simple mixtures are often analyzed by direct infusion more complex mixtures (such as proteolytic digests) generally require either on-line or off-line HPLC fractionation prior to MS analysis. 

Figure 5. Methods employed for identifiying and characterizing proteins separated by 2DE. Abbreviations used 2DE, two-dimensional electrophoresis ESI, electrospray ionization HPLC, high performance liquid chromatography IR, infrared M, relative molecular mass MALDI, matrix-assisted laser desorption ionization MS, mass spectrometry MS/MS tandem mass spectrometry p/, isoelectric point PSD, post-source decay.

W. J. Griffiths, S. Liu, G. Alvelius, and J. Sjovall, Derivatization for the characterization of neutral steroids by electrospray ionization and MALDI tandem mass... 

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