El, electron impact

PCI, positive chemical ionisation El, electron impact CID, collisionally induced dissociation. 

A Finnigan MAT TSQ mass spectrometer was used to record the mass spectra of brinzolamide. The conditions were 0.3 mA current, 1100-volt acceleration voltage and 10 preamp sensitivity. The ionization voltage was 70 eV for El (electron impact) ionization mode. For Cl (chemical ionization) mode, a positive ionization voltage of 100 eV and a pressure of 0.3 torr of methane were used. The El and Cl spectra are shown in Figures 12 and 13, respectively. Peak assignments for the El and Cl spectra are listed in Table 6. Both the Cl and El spectra have an MH peak at m/z = 384. 

Figure 14.1 Schematic view of a mass spectrometer. Its basic parts are ion source, mass analyzer, and detector. Selected principles realized in modern mass spectrometers are assigned El—electron impact. Cl—chemical ionization, FAB—fast atom bombardment, ESI—electrospray ionization, MALDI—matrix-assisted laser desorption/ionization. Different combinations of ion formation with mass separation can be realized.

MS, Mass spectrometry El, electron impact Cl, chemical ionization MID, multiple ion detection PICI, positive-ion chemical ionization NICI, negative-ion chemical ionization SIM, selected ion nmonitoring TSP, thermospray PPINICI, pulsed positive ion-negative ion chemical ionization ECD, electron-capture detector NPD, nitrogen/phosphorous detector NSTD, nitrogen-selective thermionic detector FT-IR, Fourier transform infrared spectrometry. 

TD-IT, Thermal desorption-ion trap CAD MIKE, collisionally activated decomposition mass-analyzed ion kinetic energy MID, multiple ion detection FID, flame ionization detector NPD, nitrogen/phosphorus detector SIM, selected ion monitoring El, electron impact TMS, trimethylsilane MTBSTFA, N-methyl-N-(tetr.-butyldimethylsilyl)trifluoroacetamide. 

Figure A.3A.1 Flow chart illustrating the selection of a suitable ionization technique for the mass spectrometric analysis of a sample. Abbreviations APCI, atmospheric pressure chemical ionization Cl, chemical ionization El, electron impact FAB, fast atom bombardment MALDI, matrix-assisted laser desorption/ionization.

Scheme 10. Cl = chemical ionization El = electron-impact ionization.

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