Electron bombardment mass spectrometry

Electron bombardement mass spectrometry 200 Mg Lead tetramethyl Collins et al (1951) Kollar et al (1960) Ulrych and Russell (1964)... 

In addition, especially in the processed urushi samples, peaks with masses [M]K" =665 daltons and [M]K" =667 daltons which are the expected products of the dimerization reaction by oxidation of the phenol part of the catechol derivatives of urushiol. Supercritical fluid chromatography in combination with electron bombardment mass spectrometry was then used for the identification of some of the major components of the urushiol samples. Most prominently were found the trienes with [M]=314 daltons, and [M]=317 daltons and the monoenes. Again the compound with the mass of [M]=332 daltons was noticed which was the water adduct of the triene [M]=314 daltons. 

Note. Abbreviations g.l.c., gas-liquid chromatography e.i.-m.s., electron-impact mass spectrometry c.i.-m.s., chemical-ionization mass spectrometry h.p.l.c., high-performance liquid chromatography h.p.a.e., high pH anion-exchange f.a.b.-m.s., fast-atom-bombardment mass spectrometry l.s.i.-m.s., liquid secondary-ion mass spectrometry n.O.e., nuclear Overhauser enhancement. Details of these methodologies are given in Ref. (3). 

Several recent reviews can provide the reader with an historical perspective and information about additional applications of chemical ionization mass spectrometry. (7-10) Under normal conditions, electron impact mass spectrometry is carried out by bombarding sample molecules with 70 eV electrons in a mass spectrometer ion source... 

The isotopic ratios, altered by spike additions, are then measured on a portion of the sample by mass spectrometry. Even though the method is limited to elements having two or more naturally occurring or long lived isotopes, it is very sensitive and accurate and relatively free from interference effects. Thus, it has a great advantage over other analytical techniques. Thermal source and electron bombardment mass spectrom-... 

Abbreviations m/z is the mass-to-charge ratio, M is the molecular weight of the molecule itself, M+ is the molecular ion, HRMS is high-resolution mass spectrometry, FAB is fast atom bombardment, and EIMS is electron-impact mass spectrometry. 

Selected ion monitoring (SIM) and fast atom bombardment (FAB) techniques of mass spectrometry have been used for detection and quantification of different crystalline forms of triamterene. The use of electron impact mass spectrometry in the analysis of diuretic agents has been described. 

HREIMS, high resolution electron impact mass spectrometry HRFABMS, high resolution fast atom bombardment mass spectrometry. 

HPLC methods previously described (22.24.26.42). The cinnamoyl ester-bearing compounds were detected by uitraviolet (UV) monitoring at 280 nm. Structure elucidation of the purified compounds was carried out by means of infrared (iR) and UV spectrophotometry, proton and carbon-13 nuciear magnetic resonance (NMR) spectroscopy, and electron impact (EI-) and fast-atom bombardment mass spectrometry (FAB-MS). The structures of the two new isolates and three of their derivatives were established on the basis of spectroscopic data and spectrai evidence obtained on comparison with azadirachtin (23). 

It may at first appear at variance with the rest of the handbook to discuss derivatization for fast atom/ ion bombardment mass spectrometry, where chromatography may be only incidentally rather than directly involved. Nevertheless, it seems appropriate to include this aspect because these techniques are complementary to the electron impact and chemical ionization methods used with gas chromatography—mass spectrometry (GC-MS) as described in Chapter 14, and thus extend the coverage to include derivatization methods for the majority of mass spectrometric techniques. 

One problem with analyzing polymer surfaces with SIMS is static charging caused by the primary ion current. In Briggs s work [78,79], the ion current was neutralized with an electron gun. Recent developments in the analysis of polymer surfaces by mass spectrometry have included a gun that will bombard the solid surface with neutral atom bombardment, referred to as fast atom bombardment mass spectrometry (FABMS), greatly reduces the static charging problem encountered in the normal SIMS experiment. 

Oka, H. Ikai, Y. Kawamura, N. Hayakawa, J. Harada, K.-I. Murata, H. Suzuki, M. Direct interfacing of high-speed countercurrent chromatography to frit electron ionization, chemical ionization, and fast atom bombardment mass spectrometry. Anal. Chem. 1991, 63, 2861-2865. 

Fast Atom Bombardment-Mass Spectrometry (FAB-MS) and Electron Impact-Mass (EI-MS) Spectrometry... 

Lattimer and co-workers [25] have applied mass spectrometry (MS) to the determination of antioxidants and antiozonants in rubber vulcanisates. Direct thermal desorption was used with three different ionisation methods [electron impact (El), chemical ionisation (Cl), field ionisation (FI)]. The vulcanisates were also examined by direct fast atom bombardment mass spectrometry (FAB-MS) as a means for surface desorption/ionisation. Rubber extracts were examined directly by these four ionisation methods. Of the various vaporisation/ionisation methods, it appears that field ionisation is the most efficient for identifying organic additives in the rubber vulcanisates. Other ionisation methods may be required, however, for detection of specific types of additives. There was no clear advantage for direct analysis as compared to extract analysis. Antiozonants examined include aromatic amines and a hindered bisphenol. These compounds could be identified quite readily by either extraction or direct analysis and by use of any vaporisation/ionisation method. 

Investigation of interfacial effects and interactions between biocompounds and transducer surfaces at the molecular and atomic levels by exploiting new methods of surface analysis (e,g scanning microscopy techniques, fast-atomic-bombardment mass spectrometry, laser-assisted mass spectrometry, time-of-flight secondary ion mass spectrometry, Fourier-transform infrared spectrometry, ellipsometry. X-ray photoelectron spectroscopy, and electron microscopy)... 

If a sample solution is introduced into the center of the plasma, the constituent molecules are bombarded by the energetic atoms, ions, electrons, and even photons from the plasma itself. Under these vigorous conditions, sample molecules are both ionized and fragmented repeatedly until only their constituent elemental atoms or ions survive. The ions are drawn off into a mass analyzer for measurement of abundances and mJz values. Plasma torches provide a powerful method for introducing and ionizing a wide range of sample types into a mass spectrometer (inductively coupled plasma mass spectrometry, ICP/MS). 

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