CID mass spectra

LC/MS/MS with selected reaction monitoring and ESI in the negative-ion mode was used to detect RDX and its degradation products in contaminated groundwater [18]. The detected degradation products were MNX (hexahydro-l-nitroso-3,5-dinitro-l,3,5-triazine), DNX (hexahydro-l,3-dinitroso-5-nitro-l,3,5-triazine) and TNX (hexahydro-l,3,5-trinitroso-l,3,5-triazine). The [M + 75] and [M + 45] were the most intense ions in the mass spectra of RDX and its degradation products. In the CID mass spectra, the base peak for RDX, MNX and DNX... 

Bylka, W., Franski, R., and Stobiecki, M., Differentiation between isomeric acacetin-6-C-(6"-0-malonyl)glucoside and acacetin-8-C-(6"-0-malonyl)glucoside by using low-energy CID mass spectra, J. Mass Spectrom., 37, 648, 2002. 

The El and CID mass spectra of CH2X2+ (X = Cl, Br and I) were also studied100. Large kinetic energy release (KER) values were measured for the fragmentation of the molecular ion to X2+ (X = Cl and Br), leading to the proposal that the CH2 elimination involves a bridged transition state (Scheme 17). 

The determination of several modified bases has been achieved by McCloskey, using partial silylation techniques. The FD collision-induced-dissociation (CID) mass spectra of a modified nucleotide has been reported by Straub during the course of his study on the interaction of a chemical carcinogen with DNA. In that particular experiment, however, the adduct was previously separated by extraction it was not a direct application of the FD-CID technique to a structural problem. Nevertheless, the study indicated that the attachment of the carcinogenic compound takes place at the base, confirming the potential of this technique for cancer research. ... 

Fig. 5.30. CID mass spectra of mass-selected, dicationic tweezer-viologen complexes (CO top two rows, Cl third row, C2 bottom row). The second trace shows a double-resonance experiment, which is a CID experiment during which the fragment at m/z 1059 was constantly ejected. All consecutive fragments are thus not formed and can easily be identified.

Dua et al. employed collision-induced dissociation (CID) mass spectra to produce molecular precursors that were selected to yield OSCN , ONCS , and OCNS (23). When combined with the aforementioned theoretical calculations, the CID spectra provided evidence that OSCN is a product of the oxidation of SCN by H2O2, but it was suggested that some of the other ions that were observed by Arlandson et al. were possibly due to ONCS (or other isomers). In addition to conflicting conclusions that arise when comparing the aforementioned theoretical and spectroscopic studies, it is noted that many of the experimental results that have been previously reported appear to be inconsistent with the estimated lifetimes of h5rpothiocyanite under the conditions of the experiments (vide infra). 

W. M. Hines, et al., Pattern-based algorithm for peptide seqnencing from tandem high-energy CID mass spectra, J. Am. Soc. Mass Spectrom. 3, 326-361 (1992). 

A key question in NR MS experiments is whether or not the intermediate neutrals retain the atom connectivity of the precursor ions. Structures of neutrals generated in NR MS experiments can be elucidated by comparison of CID mass spectra of the ion prior to their neutralization with CID mass spectra of the ions surviving neutralization-reionization. If the CID mass spectra are close to each other then it is a good indication that the structures of the ions before and after the NR event are the same. 

The observation of significant differences between the CID mass spectra of the ions before neutralization and after reionization usually indicates that the intermediate neutrals did not retain... 

Figure 4 (b) CID mass spectra of mass-selected [wheel- -H]+ at different collision energies. The fragmentation pathways can be... 

Fig. 7.8 High-energy CID mass spectra of erythromycin A with either the FAB-generated [M + H] -ion top spectrum) or [M + K]+-ion bottom spectrum) as precursor ions. (Reprinted from [123] with kind permission from Springer Science and Business Media)...

Fig. 7.9 Low-energy CID mass spectra of globularin with either the ESI-generated [M+H] -ion (left-hand spectrum) or[M+Na] -ion( right-hand spectrum) as precursor ions. See text for further explanation and interpretation. (Reprinted fiom [163] with permission of Wiley copyright 2007, John Wiley and Sons, Ltd)...

Phospholipids have been studied by means of maity condensed-phase ionization techniques. In the FAB-MS mass spectra of GPCho, the three most abundant ions were [M+H]+, [M+Na]+, and a fragment ion [M+Na-59]+ due to the loss of trimethylamine. CID mass spectra with [M+Na]+ as precursor ion resulted in the loss of the fatty acids and the loss of choline phosphate, thus [M+Na-183]+,... 

ESI for eicosanoid analysis has been in the negative-ion mode [18]. In this section, a few examples of CID mass spectra of eicosanoid species are given, whereas general description of these CID spectra is referred to an excellent review article written by Dr Murphy and colleagues [18],... 

Figure 3 Unmerged ion chromatograms for three coeluting octachlorinated compounds. Each chromatogram is composed from the signal intensities of the ion species identified on the ordinate, (a) The fragment ion signal intensities were obtained from CID mass spectra and one such mass spectrum is displayed for each compound, (b) The isolated molecular ion signal intensities were obtained prior to CID and a mass spectrum showing the isolated molecular ions is displayed for each compound.

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