Desorption continued electrospray ionization

DGE a AC AMS APCI API AP-MALDI APPI ASAP BIRD c CAD CE CF CF-FAB Cl CID cw CZE Da DAPCI DART DC DE DESI DIOS DTIMS EC ECD El ELDI EM ESI ETD eV f FAB FAIMS FD FI FT FTICR two-dimensional gel electrophoresis atto, 10 18 alternating current accelerator mass spectrometry atmospheric pressure chemical ionization atmospheric pressure ionization atmospheric pressure matrix-assisted laser desorption/ionization atmospheric pressure photoionization atmospheric-pressure solids analysis probe blackbody infrared radiative dissociation centi, 10-2 collision-activated dissociation capillary electrophoresis continuous flow continuous flow fast atom bombardment chemical ionization collision-induced dissociation continuous wave capillary zone electrophoresis dalton desorption atmospheric pressure chemical ionization direct analysis in real time direct current delayed extraction desorption electrospray ionization desorption/ionization on silicon drift tube ion mobility spectrometry electrochromatography electron capture dissociation electron ionization electrospray-assisted laser desorption/ionization electron multiplier electrospray ionization electron transfer dissociation electron volt femto, 1CT15 fast atom bombardment field asymmetric waveform ion mobility spectrometry field desorption field ionization Fourier transform Fourier transform ion cyclotron resonance... 

At the beginning of the 1990s, two new ionization methods, electrospray ionization (ESI) [9] and matrix-assisted laser desorption/ionization (MALDI) coupled to time-of-flight (TOF) analysers [10] that avoided such inconveniences, were developed and continue to revolutionize the role of mass spectrometry in biological research. These methods allow the high-precision analysis of biomolecules of very high molecular weight. 

An ideal interface should not cause extra-column peak broadening. Historical interfaces include the moving belt and the thermospray. Common interfaces are electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCl). Several special interfaces include the particle beam—a pioneering technique that is still used because it is the only one that can provide electron ionization mass spectra. Others are continuous fiow fast atom bombardment (CF-FAB), atmospheric pressure photon ionization (APPI), and matrix-assisted laser desorption ionization (M ALDl). The two most common interfaces, ESI and APCI, were discovered in the late 1980s and involve an atmospheric pressure ionization (API) step. Both are soft ionization techniques that cause little or no fragmentation hence a fingerprint for qualitative identification is usually not apparent. 

Earlier methods of ionization applied to carotenoids, including electron impact (El), chemical ionization (Cl), a particle beam interface with El or Cl, and continuous-flow fast atom bombardment (CF-FAB), have been comprehensively reviewed elsewhere (van Breemen, 1996, 1997 Pajkovic and van Breemen, 2005). These techniques have generally been replaced by softer ionization techniques like electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), and more recently atmospheric pressure photoionization (APPI). It should be noted that ESI, APCI, and APPI can be used as ionization methods with a direct infusion of an analyte in solution (i.e. not interfaced with an HPLC system), or as the interface between the HPEC and the MS. In contrast, matrix-assisted laser desorption ionization (MALDI) cannot be used directly with HPEC. 

Mass spectrometrie techniques that include continuous flow fast atom bombardment (FAB), electrospray ionization (ESI), and matrix assisted laser desorption (MALDI) have been applied successfully to protein structure investigations. (3) The hyphenation of electrospray ionization mass... 

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. 

Several ionization methods have been applied for CE-MS couphng. Matrix-assisted laser desorption ionization (MALDI), continuous flow fast atom bombardment (FAB), laser vaporization ionization with UV laser, sonic spray ionization and electrospray ionization (ESI) have all been used for coupling CE to MS. However, ESI is now undoubtedly the most widely used ionization technique, employing numerous analyzers including quadrupoles, magnetic sector, Fourier transform ion cyclotron resonance, time-offlight and trapping devices. However, quad-rupole detectors have predominantly been applied in CE-MS [6-8]. 

Recent advances in protein analysis by MS are due to the introduction of electrospray ionization (ESI), matrix-assisted laser desorption ionization (MALDI), MSN scan modes, as well as improvements in instrument sensitivity, resolution, and mass accuracy. With these improved techniques, researchers will continue to use MS to help elucidate primary, secondary, and to a lesser extent, tertiary structure of proteins. 

Because a defined start-stop signal is required for the measurement of time, an essential prerequisite in the TOP operation is that all ions enter the flight tube at exactly the same time. This arrangement would also avoid any artifact left behind from the previous ionization event. For this reason, TOP instruments are optimally combined with pulsed-mode ion sources such as Cf plasma desorption or MALDI. Alternatively, pulsing the accelerating potential can provide a pulsed ion beam from continuous ion beam sources (e.g., electron ionization, and electrospray ionization). 

Off-Line Reaction Monitoring For slow enzyme reactions and long-lived intermediates, off-line reaction monitoring is more convenient. In these methods, the known amounts of an enzyme and a substrate are mixed together and incubated at physiological conditions. Aliquots are withdrawn at predetermined intervals, and the reaction is quenched immediately. The time course of the reaction can be monitored with mass spectrometric analysis immediately or later, at a more convenient time, by using either fast atom bombardment (FAB) [7], continuous-flow (CF)-FAB [7], matrix-assisted laser desorption/ionization (MALDI) [8], or electrospray ionization (ESI) [9-11]. Established quantitation procedures can be employed to monitor the concentration of the reactant or product (usually, the latter) (see Chapter 14). As an example, an appropriate internal standard that has no affinity for the enzyme can be added to the reaction mixture to improve... 

MS is undoubtedly the solution of the near future for LC detection. Improvements made to interfacing devices together with a continuous and sensible diminution of instrumentation costs promote MS as a universal/selective tunable detection system. Atmospheric pressrue electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) are the most robust and popular devices for interfacing MS to LC systems. In Table 9, LC-MS data for some pesticides are given. Although ESI and APCI are more often used, other LC-MS interfaces produce reliable results in pesticide applications thermospray (TSI), particle beam (PBI) and matrix-assisted postsource decay laser desorption/ionization (CID-PSD-MALDI). 

Advances in spectroscopic characterization continue to drive the development of the field. A number of studies describing the mass spectrometry of medium- and high-nuclearity ruthenium and osmium carbonyl clusters have been reported, including UV-laser desorption, laser desorption/ionization time-of-flight and energy-dependent electrospray ionization the last mentioned has been shown to resolve mixtures of cluster compounds. 

Fast atom bombardment, liquid-SIMS (secondary ion mass spectrometry), electrospray (ESI), and matrix assisted laser desorption (MALDI) ionization modes have been applied successfully for the investigations of biomolecules.However, ESI and MALDI are the two most frequently adopted techniques for investigations of biopolymersDetails involving the principles and application of all of these techniques can be found elsewhere. The samples may be introduced either directly or after liquid chromatographic separation. All of the above techniques, with the exception of MALDI, have been adopted for the LC/MS experiments. " Although most of the reported LC/MS investigations involved the electrospray ionization of the molecules, continuous flow-FAB ionization techniques have also been found useful. 

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