Collision-induced dissociations method

Relatively few investigations involving palladium carbonyl clusters have been carried out, partly because palladium per se does not form stable, discrete homometallic carbonyl clusters at room temperature in either solid or solution states.114,917-922 Nevertheless, solution-phase palladium carbonyl complexes have been synthesized with other stabilizing ligands (e.g., phosphines),105,923 and carbon monoxide readily absorbs on palladium surfaces.924 Moreover, gas-phase [Pd3(CO)n]-anions (n = 1-6) have been generated and their binding energies determined via the collision-induced dissociation method.925... 

Sequence information can be obtained for peptides with molecular weights up to 2500 Da. Collision-induced dissociation of larger peptides reveal at least partial sequence information that will often suffice to solve a particular problem. The collision-induced dissociation method has been particularly useful on peptides from proteolytic digests, from which MS/MS data on different peptides can help identify the structure of a digested protein. 

Hayes, R.N. Gross, M.L. Collision induced dissociation. Methods Enzymol. 1990,193, 237-263. 

Biemann, K. (1990) Sequencing of peptides by tandem mass spectrometry and high-energy collision-induced dissociation. Methods Enzymol., 193, 455-479. 

The energetics of the decarboxylation of [Fe(CO)4(COOH)] in the gas phase have been studied by collision induced dissociation methods contrary to previous opinion, no additional base catalyst is necessary.53 Treatment of [Fe(CO)4(COR)]- (R = long chain alkyl) with CuCl provides a high yield route to the diketones RCOCOR.54 Reaction of [HFe(CO)4] with styrene gives [Fe2(CO)8]2-and ethylbenzene, presumably via a [Fe(CO)4(CHMePh)] intermediate.55 The interaction of Na2[Fe(CO)4] with [MnMe(CO)5] or [CpMo(CO)3Me] gave [Fe(CO)4Me] and the appropriate metal carbonylate in first order processes [ReMe(CO)5] reacted only slowly, and [FpMe] not at all.56... 

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. 

Surface methyls have also been synthesized by the collision-induced dissociation of methane physisorbed on Ni(lll) surfaces.[7, 8] This approach avoids the effects of coadsorbates other than hydrogen, and a number of aspects of Ae reaction and decomposition of CH3 and CH fragments on Ni(lll) have been determined.[9] However, the method is relatively complex and best suited for study of low coverages. 

Substituted tetrazoles reacting in the mass spectrometer with acyl ions afforded 2,5-disubstituted 1,3,4-oxadiazoles with nitrogen loss. Tandem mass spectrometry allowed for the collision-induced dissociation of the products. Chemical ionization was the better method to make the transformation. A scheme for the transformation of 5-substituted tetrazoles into 2,5-disubstituted 1,3,4-oxadiazoles was proposed (Scheme 1) <2001JMP1069>. The fragmentation patterns of monocyclic l,3,4-oxadiazolium-2-thiolates have been proposed by Ollis and Ramsden <1974J(P1)645>. 

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. 

The localization of a double bond is an important step in structure elucidation and therefore, it is not astonishing that numerous approaches have been made to overcome the above limitations. The methods to freeze isomerization include i) epoxidation [64], ii) iron and copper ion chemical ionization [65,66], iii) field ionization [67], iv) collision-induced dissociation [60], v) formation of thioether derivatives, [68,69] and others. 

Muller, C., Schafer, P., Stortzel, M., Vogt, S., and Weinmann, W. (2002). Ion suppression effects in liquid chromatography-electrospray-ionization transport-region collision induced dissociation mass spectrometry with different serum extraction methods for systematic toxicological analysis with mass spectra libraries. /. Chromatogr. B 773, 47— 52. 

In this chapter, we give an overview on how the API techniques work and which factors have an important influence on the performance. Examples are presented mostly from published work to demonstrate how LC-MS, LC-MS-MS, collision-induced dissociations (CIDs), accurate mass measurements and hydro-gen/deuterium exchange have been systematically and successfully applied in the structural elucidation of impurities, degradation products and metabolites. In addition, these also illustrate how mass spectrometry has offered a third dimension to chromatographic method development and validation. 

The structures of protonated azoles in the gas phase (equilibrium ) can be determined by mass spectrometry in a chemical ionization experiment followed by collision-induced dissociation. The method has been used to study the protonation of benzimidazole (5), indazole (7), and 1-ethylimidazole (179) (all, as expected, on the pyridinelike nitrogen atoms) (80OMSI44) of 1-ethylpyrrole (probably at the -position) (80OMS144) and indole (at the -position) (85IJM49) (see Section IV.A). 

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