Electron spray ionization mass spectrometry

Castellanos-Santiago E and Yahia EM. 2008. Identification and quantification of betalaines from the fruits of 10 Mexican prickly pear cultivars by high-performance liquid chromatography and electron spray ionization mass spectrometry. J Agric Food Chem 56 5758-5764. 

The native molecular weight (M) of 83.0 kdal is determined independently with electron spray ionization mass spectrometry. If the protein is spherical and unhydrated, its radius (r0) can be estimated by... 

The thus prepared ligands la-le-H4 are introduced into coordination studies with titanium(IV) ions in the presence of base (M2C03 M = Li, Na, K) with methanol as solvent. Negative ESI-MS (electron spray ionization mass spectrometry) of the obtained orange-red solids in methanol reveals that coordination compounds of general formula M2[l2(OCH3)2Ti2] are formed (Scheme 1.3.2) [20, 21]. 

Identification of different reaction products or different peaks from chromatograms is done by using standards or performing mass spectrometry. MALDI-TOF is an ionization technique frequently used. Also, combined setups can be found like LC-MS or UPLC-ESI-MS (electron spray ionization mass spectrometry) profiles. ... 

Capillary Zone Electrophoresis with Electron-Spray Ionization-Mass Spectrometry Detection... 

Figure 1.13 Selected analytical techniques used for metallomics studies. ICP-OES, inductively coupled plasma optical emission spectroscopy, ICP-MS, inductively coupled plasma mass spectrometry LA-ICP-MS, laser ablation ICP-MS XRF, X-ray fluorescence spectroscopy PIXE, proton induced X-ray emission NAA, neutron activation analysis SIMS, secondary ion mass spectroscopy GE, gel electrophoresis LC, liquid chromatography GC, gas chromatography MS, mass spectrometry, which includes MALDI-TOF-MS, matrix-assisted laser desorption/ ionization time of flight mass spectrometry and ESI-MS, electron spray ionization mass spectrometry NMR, nuclear magnetic resonance PX, protein crystallography XAS, X-ray absorption spectroscopy NS, neutron scattering.

In 2010, Xia, Huang and co-workers reported an iron-assisted chiral phosphoric acid catalyst for the Fridel-Crafts reaction between indole and 3-aryl a -hydroxy enones (Fig. 16) [70]. Due to the evidence from electron spray ionization mass spectrometry (ESI-MS) analysis for the presence of iron phosphate salt, an iron/ proton dual activation mechanism was proposed to account the observed reactivity/ selectivity trends. Addition of a third acid component, silver triflate, was shown to be beneficial for the enantioselectivity, presumably by exchanging chloride to the less coordinating triflate anion. 

Latter on, de Souza and colleagues studied the mechanism of Bigjnelli reaction with mass spectrometry by direct infusion electrospray (electron-spray ionization mass spectroscopy, ESl-MS) [8]. In their studies, they found that reacting benz-aldehyde and urea leads to the formation of ions of m/z 209,167, and 149 (Figure 4). When the reaction was carried out with the three components (xuea, acetoacetate, and benzaldehyde), existences of the same intermediates were also detected. 

Hamscher G., S. Sczesny, H. Hdper, and H. Nau (2002). Determination of persistent tetracycline residues in soil fertilized with liquid manure by high-performance liquid chromatography with electron spray ionization tandem mass spectrometry. Analytical Cheminstry 74 1509-1518. 

Mass spectrometry (MS) is a very sensitive method of determining the mass of native proteins, as well as their purity. The two most common techniques are ESI-MS (electron spray ionization-MS) and MALDI-TOF-MS (matrix-assisted laser... 

Boroles have been routinely analyzed by mass spectrometry but only as far as to deduce their molecular mass. Electron impact, chemical ionization, and electron spray ionization methods have been used. No reports on the fragmentation patterns of boroles have been published to date. 

Fig. 29. Experimental setup for SEC coupled to Fourier transform mass spectrometry via an electron spray ionization source. Reproduced from [169] with permission...

Aaserud et al. reported an on-line coupling of SEC to Fourier transform mass spectrometry (FT-MS) using a modified commercial electron spray ionization (ESI) interface (Fig. 29) [169]. They analyzed a glycidyl methacrylate/butyl methacrylate copolymer with a broad molecular weight distribution, where fractionation and high resolving power were required for adequate characterization. The SEC/ESI/FT-MS also allowed for an unequivocal end-group determination and characterization of a secondary distribution due to the formation of cyclic reaction products. 

Recently, we have used electron spray ionization Fourier transform ion cyclotron mass spectrometry (ESI-FTICRMS) to intercept and characterize several organome-tallic species in Pd-catalyzed reactions of 2,3-allenoate with two organoboronic adds... 

After separation, the compounds are ionized prior to mass analysis. The most common techniques for ionization include chemical ionization (Cl), electron impact (El), electron spray ionization (ESI), and matrix-assisted laser desorption ionization (MALDI). Charged compounds are shutded into the mass analyzer which, depending upon the method, selects ions based on predetermined mass-to-charge ratio m/z) criteria, or scans within defined m/z ranges. If tandem mass spectrometry (MS/MS) is... 

Methods other than electron bombardment (EI-MS) can be used to obtain mass spectral data. In chemical ionization-mass spectrometry (CI-MS), the sample is sprayed with a pre-ionized gas such as methane or ammonia that causes the sample to ionize by electron transfer or proton transfer from the gas to the sample. Because the molecular ions produced by this technique are less apt to undergo fragmentation, the ability to obtain the molecular mass (and therefore the molecular formula) of the sample is enhanced. 

For a molecular compound, the full molecular formula can be established from the empirical formula and the molecular mass (RMM). Various physical properties, including the vapour density of a gas, and so-called colligative properties (such as freezing point depression) in solution, can be used to determine the RMM. However the most important technique in modem research is mass spectrometry (MS) where molecular ions are accelerated in an electric field, and then pass through a magnetic field where their paths are bent to an extent that depends on the mass/charge ratio. The traditional MS method requires a volatile sample, ionized by electron bombardment, but methods are now available that overcome the limitations of that method. Direct desorption from solids by a laser beam or by fast atom bombardment (FAB) allow measurement of involatile compounds. Solutions may also be sprayed directly into the spectrometer inlet and the spectrum measured after the solvent has evaporated. 

For these classes of substances, other methods have been developed, such as the coupling of ESI with an electrochemical cell [20-31], the coordination ion-spray [31-46], or the dissociative electron-capture ionization [37-41]. The APPI or the dopant-assisted (DA) APPI presented by Syage et al. [42, 43] and Robb et al. [44,45], respectively, are relatively new methods for photoionization (PI) of nonpolar substances by means of vacuum ultraviolet (VUV) radiation. Both techniques are based on photoionization, which is also used in ion mobility mass spectrometry [46-49] and in the photoionization detector (PID) [50- 52]. 

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