Search results for "COLLISION-INDUCED DISSOCIATION"

Optimization of Resolving Power, Fragmentation, and Mass Calibration in an Orbitrap Spectrometer for Analysis of 24 Pesticide Metabolites in Urine

2019

Mass spectrometer parameters such as Resolving Power, type of fragmentation, and mass calibration mode were optimized in the analysis of 24 pesticide metabolites in human urine using Ultra-High Pressure Liquid Chromatography coupled to Orbitrap High-Resolution Mass Spectrometer (UHPLC-HRMS). The best results were achieved with a Resolving Power of 25,000 FWHM and by applying Collision Induced Dissociation fragmentation mode (40 eV).

Fission barriers of doubly charged silver clusters

1999

The monomer evaporation energies and fission barriers of doubly charged silver cluster ions in the size range 9≤n≤25 are measured by collision induced dissociation. They are compared to the dissociation energies of singly charged silver clusters. A macroscopic liquid drop model combined with empirical microscopic corrections successfully describes the measured fission barriers.

Collision induced dissociation of doubly charged stored metal cluster ions

1997

Effect of protonation and deprotonation on the gas phase reactivity of fluorinated 1,2,4-triazines

2008

Positive and negative electrospray mass spectrometry (MS), in-time and in-space MS n experiments, high-resolution and accurate mass measurements obtained with an Orbitrap, together with density functional theory calculations have been used to study the gas-phase ion chemistry of a series of fluorinated 1,2,4-triazines. As a result of low-energy collision-induced dissociations, occurring in an ion trap and in a triple quadrupole, their protonated and deprotonated molecules show interesting features depending on the nature and structure of the precursor ions. The occurrence of elimination/hydration reactions produced by positive ions in the ion trap is noteworthy. Decompositions of deprotonat…

Production and investigation of multiply charged metal clusters in a Penning trap

1996

Singly charged gold cluster ions from a laser-vaporization source are transferred into a Penning trap and subjected to electron bombardment. The charged reaction products are analyzed by time-of-flight mass spectrometry after axial ejection from the trap. They include singly charged cluster fragments, multiply charged clusters of the initial size and multiply charged cluster fragments. The multiply charged clusters are selected and further investigated by collision induced dissociation. Two types of reactions can be distinguished: Dissociation into several charged fragments and evaporation of neutrals. Several features of multiply charged clusters relevant for future investigations are revi…

The Mainz Cluster Trap

1999

When cluster ions are stored by electromagnetic forces they are available in the gas phase for extended preparations and investigations. Over the last decade a Penning trap (Ion Cyclotron Resonance) apparatus has been constructed and further developed with respect to metal cluster research at the Institute of Physics at Mainz. It allows to capture and accumulate ion bunches injected from an external cluster source and to manipulate the ions’ motion, i.e. select and center the clusters of interest. The interactions that have been investigated include those with inert and chemically reactive gases, photons and electrons. Multiple mass spectrometric steps such as fragment ion selection can be …

Observation of electronic and geometric shell structures of small silver clusters

1999

Singly charged silver clusters Open image in new window in the size range n = 17 to n = 78 have been captured and stored in a Penning trap, size selected and subjected to an electron beam which leads to further ionization as well as dissociation. The resulting abundance spectra of doubly and triply charged clusters show several features: (1) A critical size for the production of doubly charged clusters which can be understood in terms of the decay pathways as previously investigated by collision induced dissociation, (2) an odd-even alternation in the abundance of singly and doubly charged clusters which inverses sign with change of charge state, (3) prominent signals for particular doubly …

Experimental dissociation energies of metal cluster dications and their interpretation in a liquid-drop model with empirical corrections

1999

The dissociation energies of doubly charged silver cluster ions in the size range $9l~nl~25$ are measured by multiple collision induced dissociation. They are compared to the dissociation energies of singly charged clusters. To this end, the latter are used to calculate shell corrections in a macroscopic-microscopic model. Good agreement between the resulting predictions of the dissociation energies of the doubly charged systems and the experimental values is found, which indicates the strong influence of electronic effects on the stability of small silver clusters.

An electrospray ionization Fourier transform ion cyclotron resonance mass spectrometric study of the gas-phase stabilities and fragmentation ofN-alky…

2006

Five N-alkylated ammonium resorcarene derivatives, differing either in the nitrogen atom or in the lower rim alkyl chain, were studied using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The main purpose was to clarify the fragmentation and the relative stabilities of the protonated molecules by collision-induced dissociation (CID) experiments. The results indicate that fragmentation of the upper rim alkyl amino substituents at the 2-position occurs readily. Variation in the gas-phase stabilities of these molecules was also observed. In addition, the proposed fragmentation pathways are depicted.

Entrapment of amino acids in gas phase surfactant assemblies: The case of tryptophan confined in positively charged (1R,2S)-dodecyl (2-hydroxy-1-meth…

2017

The ability of positively charged aggregates of the surfactant (1R,2S)‐dodecyl (2‐hydroxy‐1‐methyl‐2‐phenylethyl))dimethylammonium bromide (DMEB) to incorporate D-tryptophan or L-tryptophan in the gas phase has been investigated by electrospray ion mobility mass spectrometry (ESI‐IM‐MS). Strongly impacted by the pH of the electrosprayed solutions, both protonated (T+) and deprotonated (T-) tryptophan are effectively included into the aggregates, whereas, tryptophan in zwitterionic (T0) form is practically absent in singly charged DMEB aggregates but can be found in multiply charged ones. The ability to incorporate tryptophan increases with the aggregation number and charge state of aggr…