Matrix-assisted laser desorption ionization chemical structures

The method of choice for elucidating chemical stmctures is NMR spectroscopy, supplemented by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). In addition, a multitude of chromatographic and light-scattering methods provide access to the molecular weights and solution properties of these macromolecules. Based on these methods, a detailed understanding of the structure of hb polymers has been acquired since their discovery however, there remain a number of open questions that must be answered, mainly by method adaptation and development. 

Several mass spectrometric techniques including fast atom bombardment (FAB), plasma desorption (PD), matrix-assisted laser desorption/ionization (MALDI), and electrospray (ES) mass spectrometry (MS) are presently available for the analysis of peptides and proteins (Roepstorff and Richter, 1992). Of these techniques, mainly PDMS has gained footing in protein laboratories because the instrumentation is relatively cheap and simple to operate and because, taking advantage of a nitrocellulose matrix, it is compatible with most procedures in protein chemistry (Cotter, 1988 Roepstorff, 1989). Provided that the proper care is taken in the sample preparation procedure most peptides and small proteins (up to 10 kDa) are on a routine basis amenable to analysis by PDMS. Molecular mass information can be obtained with an accuracy of 0.1% or better. Structural information can be gained by application of successive biochemical or chemical procedures to the sample. 

In addition to these characterization tools, surface analytical techniques such as surface matrix-assisted laser desorption ionization (Surface MALDI) mass spectrometry, Rutherford backscattering spectroscopy (RBS), and near-edge X-ray absorption fine stmcture spectroscopy (NEXAFS) are used to obtain structural and chemical details about surface thin films. Surface MALDI, also known as MALDI-ToF MS (see Section 5.4.2), offers high mass resolution for analyzing surface films and molecular layers using the m/z of various ions generated from the sample surface (mixed with an... 

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