Ionization energy , mass spectrometry

Schaub, T. M., Rodgers, R. R, Marshall, A. G., Qian, K., Green, L. A., and Olmstead, W. N. (2005). Speciation of aromatic compounds in petroleum refinery streams by continuous flow field desorption ionization FTICR mass spectrometry. Energy Fuels 19,1566-1573. 

The positive electrospray ionization tandem mass spectrometry (ESTMS/ MS) of lornoxicam was obtained using an Agilent 6410 QQQ mass spectrometer with collision energy 10 eV using argon as collision gas and is shown in Fig. 6.14. Table 6.8 shows the mass fragmentation pattern of the drugs. 

Figure 8.4. The SACI/MS3 spectra of the OTA daughter ion at m/z 358 (above) and of the ZAN daughter ion at m/z 303 (below). The OTA m/z 239+341 and ZAN m/z 163+189+207 signals are used for quantitative analysis. (Spectra acquired in positive-ion mode collision energy applied to the parent ion 80% of maximum value MS3 of daughter ions at 100% of maximum collision energy). (Reprinted from Rapid Communications in Mass Spectrometry 21,Flamini et al., A new sensitive and selective method for analysis of ochratoxin A in grape and wine by direct liquid chromato-graphy/surface activated chemical ionization-tandem mass spectrometry, p. 3740, Copyright 2007, with permission from John Wiley Sons, Ltd.)...

Mueller, W., Schubert, J., Benzing, A., and Geiger, K., Method for analysis of exhaled air by microwave energy desorption coupled with gas chromatography-flame ionization detection-mass spectrometry, J. Chromatogr. B, 716, 27-38, 1998. 

Liu Y, He J, Zhang R, Shi J, Abliz Z. Study of the characteristic fragmentation behavior of hydroquinone glycosides by electrospray ionization tandem mass spectrometry with optimization of collision energy. J Mass Spectrom 2009 44 1182 1187. 

The ion with miz 15 must be a methyl carbocation formed by loss of a fluorine atom, as shown below. The fleeting existence of a methyl carbocation is possible in electron impact ionization (El) mass spectrometry (MS) because electrons with high kinetic energy bombard the species undergoing analysis, allowing higher energy pathways to be followed than occur with reactions that take place in solution. 

MATI Mass-analyzed threshold ionization— the mass spectrometry of ions produced in coincidence with zero-kinetic energy (ZEKE) electrons. 

Source Palit, M., Mallard, G. (2009) Fragmentation energy index for universalization of fragmentation energy in ion trap mass spectrometers for the analysis of chemical weapon convention related chemicals by atmospheric pressure ionization-tandem mass spectrometry analysis. Analytical Chemistry, 81,2477-2485. 

In electron ionization (El) mass spectrometry, ions are produced by bombarding gaseous molecules with high-energy electrons. It is a hard technique and causes fragmentation of the parent molecule. 

Mass spectrometry is not based on absorption of electromagnetic radia tion but monitors what happens when a substance is ionized by collision with a high energy electron... 

Although there has been some controversy concerning the processes involved in field ionization mass spectrometry, the general principles appear to be understood. Firstly, the ionization process itself produces little excess of vibrational and rotational energy in the ions, and, consequently, fragmentation is limited or nonexistent. This ionization process is one of the mild or soft methods available for producing excellent molecular mass information. The initially formed ions are either simple radical cations or radical anions (M ). 

Some of the target molecules gain so much excess internal energy in a short space of time that they lose an electron and become ions. These are the molecular cation-radicals found in mass spectrometry by the direct absorption of radiation. However, these initial ions may react with accompanying neutral molecules, as in chemical ionization, to produce protonated molecules. 

Desorption ionization (DI). General term to encompass the various procedures (e.g., secondary ion mass spectrometry, fast-atom bombardment, californium fission fragment desorption, thermal desorption) in which ions are generated directly from a solid or liquid sample by energy input. Experimental conditions must be clearly stated. 

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