Collisional activated decomposition

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). 

B. a term meaning the strength of a magnetic field, often used to refer to a magnetic field or sector B/E. a method of linked scanning for metastable ions, which uses combined m netic and electric fields B /E. a method of linked scanning for metastable ions, which uses combined magnetic and electric fields CAD. collisionally activated decomposition... 

An insight into the equilibria present in solutions of several complexes of the type (R3P)2HgX2 (X = C104, CF3COO) is provided by electrospray mass spectrometry (ES MS) (cf. Section 6.9.2.1.8). 39 In all cases the principal ions [(R3P)2HgX]+ are observed, even if these ions and other ionic constituents of the equilibria are known to be labile on the NMR timescale. In the presence of excess R3P the principal ions [(R3P)3HgX]+ appear. Also fragments of collisionally activated decomposition (CAD, can be influenced and controlled to some extent) are detected, e.g., [(R3P)HgX]+. 

Voyskner, R. D. Pack, T. Investigation of collisional-activation decomposition process and spectra in the transport oregion of an electrospray single-quadrupole mass-spectrometer. Rapid Comm. Mass Spectrom. 1991, 5, 263-268. 

Morris H.R., Paxton T., Dell A., Langhome J., Berg M., Bordoli R.S., Hoyes J., and Bateman R.H. (1996), High sensitivity collisionally-activated decomposition tandem mass spectrometry on a novel quadrupole/orthogonal-acceleration time-of-flight mass spectrometer, Rapid Commun. Mass Spectrom. 10, 889-896. 

A number of methods have been described for determination of tetracycline (chlortetracycline, tetracycline, and oxytetracycline) residues in tissues of food-producing animals (53-62), fish (63), eggs (64), and honey (65,66). Most of these methods use reversed-phase HPLC for determination. However, one uses TLC with UV densitometry ( ) and one uses GLC ( ), and one uses a direct mass spectrometric method CAD MIKE spectrometry (collisionally activated decomposition mass-analyzed ion kinetic spectrometry) for oxytetracycline in milk and meat (62). Several use solid-phase extraction in the cleanup procedure using XAD-2 resin (56,58) or Cj g cartridges... 

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. 

Rodrigues Filho et al. studied the fragmentation of dipyridamole and several of its derivatives by electrospray ionization combined with collisional activated decomposition mass spectrometry in both positive and negative modes [61]. These compounds produce abundant mono-charged ions ([M + H]+) under electrospray ionization. Interpretation of the collisional activated decomposition spectra showed that fragmentation occurs preferentially in the ethanolamine groups attached at C-2, C-4, C-6, and C-8. 2-Methoxyethanol is eliminated when ethanolamines are in positions C-2/C-6, and 2-aziridinethanol is eliminated from... 

Van der Kerk-Van Hoof, A. Heck, A.J.R. Covalent and Non-Covalent Dissociations of Gas-Phase Complexes of Avoparcin and Bacterial Receptor Mimicking Precursor Peptides Studied by Collisionally Activated Decomposition Mass Spectrometry, J. Mass Spectrom. 34, 813-819 (1999). 

Morris, H.R. Paxton, T. Dell, A. Langhorne,J. Berg, M. Bordoli, R.S. Hoyes, J. Bateman R.H. High Sensitivity Collisionally-Activated Decomposition Tandem Mass Spectrometry on a Novel Quadrupole/Orthogonal-Acceleration Time-of-Flight Mass Spectrometer, Rapid Commun. Mass Spectrom. 10(8), 889-896 (1996). 

Applications of FAB have been succesfully performed in the characterization of a wide range of compounds (dyes, surfactants, polymers...) but little attention has been devoted to the capabilities of this technique to solve environmental concerns, such as organic pollutants identification in water. The widespread use of surfactants in the environment has required the emplo yment of both sensitive and specific methods for their determination at trace levels. GC/MS and HPLC procedures has been used for the determination of anionic (LAB s) and non ionic surfactants (NPEO) in water (1-4). Levsen et al (5) identified cationic and anionic sirrfactants in surface water by combined field desorption/ collisionally activated decomposition mass spectrometry (FD/CAD), whereas FAB mass spectrometry has been used for the characterization of pine industrial surfactants (6-8). 

Collisionally activated decompositions were very close, concerning the ions produced, to those produced at 70 eV under El. 

In collisional activation conditions, DIT leads to differences in the relative efficiencies of the collisionally activated decomposition processes In the low-mass range, DIT leads to an internal energy deposition higher than that observed by QIT the opposite is true in the high-mass range. 

Conventional ionization techniques like El or Cl are less well suited for the characterization of quaternary amines, which are the most common cationic surfactants. Because of their thermal instability and low volatility their corresponding mass spectra only show decomposition products and fragment ions which make it impossible to analyze environmental samples of unknown composition. By the use of EAB-MS and FD-MS, however, ionization of quaternary amines can be achieved without decomposition. FAB spectra are characterized by strong quasimolecular ions as well as structure specific ions. ° FAB in combination with collisionally activated decomposition (CAD) in a tandem mass spectrometer enables a clear differentiation between quasimolecular and fragment ions, which is often difficult using FAB alone. FD spectra of quaternary amines are dominated by quasimolecular ions as already described for other surfactant... 

Finally, the use of linked scan or MS/MS techniques can impart even greater selectivity. In this approach, the use of collisionally activated decomposition of a parent ion to give a suitable daughter ion is monitored. For instance, in a typical MS/MS experiment on t-BDMS ethers, the first mass spectrometer MSI would pass the parent ion whilst MS2 would be set to pass the M — 57 ion. This technique is known as selective reaction monitoring. An example is shown in Figure 2, which shows the analyses of a plasma extract of oestradiol-17/1 obtained using the... 

Schuyl, P. J. W., de Joode, T., Duchateau, G. S. M. J. E. et al (1994) Negative chemical ionization and collisionally activated decomposition mass spectra of 0-2,3,4,5,6-pentafluor-obenzyloxime derivatives of prostaglandins. Biol Mass Spectrom., 23, 47-50. 

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