Collision-Induced Dissociation CID

Ions acquire additional vibrational energy through 

The CID process (in positive ion mode) is effective only for protonated molecules. If the mIz selected in the first analyzer corresponds to a sodiated species, [M -i- Na]+, then the stability of these ions results in either no fragmentation, regardless of how much energy is added, or that a point is reached where the acquired energy leads to the complete disintegration of the ion. 

CID spectra of sulfadimethoxine at collision energies of 10-50 volts. Scanning the voltage that provides the collision energy is used to generate multiple spectra with structural information. 

A specific voltage, selected to provide a sii e intense fragment, is used in selected reaction monitoring. 

The required collision energies are compound-specific and are determined empirically. 

---

By introducing a collision gas into Q2, collision-induced dissociation (CID) can be used to cause more ions to fragment (Figure 33.4). For example, with a pressure of argon in Q2, normal ions (mj ) collide with gas molecules and dissociate to give mj ions. CID increases the yield of fragments compared with natural formation of metastable ions without induced decomposition. 

Tandem quadrupole and magnetic-sector mass spectrometers as well as FT-ICR and ion trap instruments have been employed in MS/MS experiments involving precursor/product/neutral relationships. Fragmentation can be the result of a metastable decomposition or collision-induced dissociation (CID). The purpose of this type of instrumentation is to identify, qualitatively or quantitatively, specific compounds contained in complex mixtures. This method provides high sensitivity and high specificity. The instrumentation commonly applied in GC/MS is discussed under the MS/MS Instrumentation heading, which appears earlier in this chapter. 

Collision-activated dissociation (CAD) The same process as collision-induced dissociation (CID). 

Collision-induced dissociation (CID) An ionic/neutral process in which the projectile ion is dissociated as a result of interaction with a target neutral species. Part of the translational energy of the ion is converted to internal energy causing subsequent fragmentation. 

Fragmentation occurs because the repeller voltage increases the kinetic energy of the ions, not only making collision-induced dissociation (CID) more likely but also allowing endothermic ion-molecule and solvent-switching reactions to occur. 

Positive ion FAB mass spectra obtained with a double focusing mass spectrometer produced abundant molecular ions ([M] +) of carotenes and xanthophyUs with minimal fragmentation and no detectable thermal decomposition. Fragmentation of the precursor ion was enhanced by collision-induced dissociation (CID) using helium gas. ... 

The use of collision-induced dissociation (CID) and MS/MS techniques in conjunction with the API interfaces has dramatically impacted the fleld of environmental analysis. These techniques are now preferred for the determination of triazine compounds in water, soil, crops, etc., owing to the significant improvements in selectivity obtained via the monitoring of precursor-product ion pairs and increased sensitivity due to the reduction of chemical noise. 

S.3.4.2. Collision-induced Dissociation/Translationally-driven Reactions Tandem-mass spectrometry can be used to determine the threshold energy for collision-induced dissociation (CID),... 

In most cases, ion activation in the reaction region or fragmentation zone is applied to increase the internal energy of the ions transmitted from the ion source. The most common means of ion activation in tandem mass spectrometry is collision-induced dissociation. CID uses gas-phase collisions between the ion and neutral target gas (such as helium, nitrogen or argon) to cause internal excitation of the ion and subsequent dissociation... 

In obtaining experimental information about the isomeric forms of ions, a variety of techniques have been used. These include ion cyclotron resonance (ICR),31 flow tube techniques, notably the selected ion flow tube (SIFT),32 and the selected ion flow drift tube (SIFDT)32 (and its simpler variant33), collision induced dissociation (CID),10,11 and the decomposition of metastable ions in mass spectrometers.13 All of these techniques are mentioned in the text of Section in whore they have provided data relevant to the present review. 

Apparatus, developed in this laboratory for two types of thermochemical measurements—(a) gas-phase ion molecule equilibria and (b) collision-induced dissociation (CID) threshold measurements—will be described. For both purposes, a triple quadrupole mass spectrometer is used. It is only the front end modifications that provide the conditions for (a) or (b). 

Giguere and Mayer [121] reported on the dissociation of gas-phase poly(vinyl acetate) (PVAc), see Figure 21, ionised by Li+ investigated by electrospray-ionisation (ESI) mass and collision induced dissociation (CID) mass spectrometry. 

The main principles of de novo sequencing will be discussed here using a few d spectra that were acquired using an ion trap mass spectrometer equipped with an electrospray ion source, under low energy collision induced dissociation (CID). 

The dissociation of gas-phase ions can be a guide to the structure of the ions. There are two ways to dissociate gas-phase ions, either by collision-induced dissociation (CID) sometimes termed collision-activation dissociation (CAD) or by photodissociation. In each method, a mass selected ion is dissociated and the fragment ion (often called a daughter ion) is measured the neutral fragment cannot be experimentally observed. 

---