Collisional-induced dissociation

A constant-mass-difference scan. Source ions (m, f,. .., fj) are passed successively by Q1 into Q2, where collisionally induced dissociation occurs. Q3 is set to pass only those ions produced in Q2 that have a predetermined mass difference (Am) between the ions passed by Ql. In this example, they are m, - f, (= Am) and f, - fj (= Am), so, although all ions pass into Q2, only f, f, have a mass difference (Am) equal to that selected for Q3. 

Collision of normal ions from the first quadrupole with gas molecules in the second quadrupole increases fragmentation, a process known as either collisionally induced dissociation (CID) or collisionally activated decomposition (CAD). 

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

Fragmentation Region metastable decay collisional induced dissociation photodissociation... 

Burgers, P.C. Holmes, J.E. Mommers, A.A. Terlouw, J.K. Neutral Products of Ion Fragmentations Hydrogen Cyanide and Hydrogen Isocyanide (HNC) Identified by Collisionally Induced Dissociative Ionization. Chem. Phys. Lett. 1983,102,1-3. 

Since both ESP and ISP produce quasimolecular ions, more sophisticated techniques, such as LC-MS-MS are required to obtain diagnostic fragment ions and, thus, analyte structure elucidation (117, 118). Identification can often be achieved by using daughter ion MS-MS scans and collisionally induced dissociation (CID), most commonly on a triple quadrupole MS in this way, dissociation of the quasimolecular ion occurs and diagnostic structural information can be obtained (119). 

Because of the importance of the biphenyl scaffold, as a structure of pharmaceutical and active therapeutic compounds, the mass spectrometric behavior of a series of 6,6-disubstituted dibenzo[r//][l,3]dioxepins 36 has been studied. The electron ionization-induced fragmentation patterns were discussed based on use of labeled compounds, accurate mass measurements, and collisionally induced dissociation experiments using an ion trap <2006JMP577>. 

E. Yoon and R. A. Laine, Linkage position determination in a novel set of permethylated neutral trisaccharides by collisional-induced dissociation and tandem mass spectrometry. Biol. Mass Spectrom., 21 (1992) 479-485. 

High-throughput bioanalysis screening approaches involve the characterization of full-scan mass spectra and MS/MS properties to determine the predominant molecular and product ions, respectively. This information is useful for the selection of appropriate ions for selected reaction monitoring (SRM) experiments. Settings such as collision energies and collisionally induced dissociation (CID) pressure or gas thickness can be optimized as well. Typically, the most abundant product ion is selected for SRM. Various acquisition software programs are used to perform the experiment, display the results, and process the data in an automated fashion. 

Fractions containing ions of interest were infused into the mass spectrometer at 1.7 lil/min. and ions selected in the first quadrupole were analyzed by interpreting collisionally induced dissociation (CID) spectra. MacBioSpec was used to generate lists of expected mass spectral fragments for comparison to the observed data. 

Figure 2. Collisionally induced dissociation (CID) spectra with doubly charged ions of a) m/z=649.4 and b) tn/z=S67.1. These spectra show that the ion at m/z=S67.1 is the b9 fragment of that at m/z 649.4. The CID specuum of the latter ion was consistent with the sequence of the known N-terminal peptide from cytochrome-C, namely Ac-Gly-Asp-Val-Glu-Lys -Gly-Lys -Lys -Ile-Phe, where the Lys residues have a deuterated acetylation. Ions labelled with an arrow pointing right are b fragment ions, those labelled with an arrow pointing left ate y fragment ions.

All mass spectra were obtained on a PE-Sciex triple quadrapole instrument (model API III) as described (3). Collisionally induced dissociation (CID) MS/MS experiments were performed in the positive ion detection mode with the orifice potential set at +50 V and the argon collision gas thickness maintained at 315 X lO molecules/ cm. Product ion scans were averaged over a range of 50-600 u in 0.1 u intervals for a dwell time of 1 msec, per interval. 

Figure 4. Collisional induced dissociation spectra of the peptide of mass 582 from the reversed phase chromatogram of peak 2 in figure 3. CID conditions are described in Methods.

The specific site of modification was established by high performance tandem MS experiments. In this technique the 12C isotope peak for the molecular ion in the first mass spectrometer is selectively introduced into an inert gas collision cell where fragmentation is induced. The fragments are separated and detected in the second mass spectrometer (22). Collisionally induced dissociation (CID) provides abundant structural information from which the amino acid sequence for the peptide (22) or, in this case, modified peptide can be deduced. 

Fig. 5. High energy collisionally induced dissociation mass spectrum for molecular ion MH+ m/z 1149 in fraction 9 (see Fig. la) corresponding to tryptic peptide P(133-144). Significant ions indicating the sequence are labeled.

Flamini, R. and Dalla Vedova, A. (2004) Fast determination of the total free resver-atrol content in wine by direct-exposure-probe, positive-ion-chemical-ionization and collisional-induced-dissociation mass spectrometry (DEP/PICI-MS/MS), Rapid Commun. Mass Spectrom. 18(17), 1925-1931. 

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