Time-delayed fragmentation

Time delayed fragmentation (TDE) Resolving (fixed) Trap/no fragment Fragment/trap/scan ... 

Hager, J. W. (2003). Product ion spectral simplification using time-delayed fragment ion capture with tandem linear ion traps. Rapid Commun. Mass Spectrom. 17 1389-1398. 

A QTRAP instrument is capable of a wide variety of scan modes full MS scan (MS), product ion scan (MS and MS ), PI scan, NL scan, MRM, predictive MRM (pMRM), multiple ion monitoring (MIM), enhanced multiply charged (EMC) scan and time-delayed fragmentation (TDF) (Hopfgartner et al., 2004 King and Fernandez-Metzler, 2006). Most of these scan modes can be incorporated into an IDA experiment to achieve metabolite detection and MS/MS spectral recording in a single run. 

In the (J-LIT hybrid [25] instruments, an ion trap is implemented as the second stage of mass analysis, either for accumulation of ions to achieve improved sensitivity after colhsion cell CID [25,46], and/or to perform MS [25,46,47]. The Q-LIT instrument can either be operated as a conventional TQ instrument or as the hybrid instrument. In TQ mode, the instrument is capable of all acquisition modes of a TQ, including SRM. In the hybrid mode, fidl-spectrum data can be acquired in the enhanced product ion (EPI) mode with up to 60-fold enhaneed sensitivity eompared to TQ instruments. Next to the enhanced multiple-charge sean and the time-delayed fragmentation scan, the system allows the acquisition of MS spectra, with the second dissociation step to be performed in the LIT [46,47]. 

Fig. 21 The temporal behavior of the ion signals for the fragments Fe(CO)n (n = 5-0). The expanded region shows the transients around time delay zero for the parent molecule and the Fe(CO)4 and Fe(CO)3 fragments. Adapted from [48]...

Two-colour photoionization spectroscopy of aniline cooled in a supersonic jet. Strong propensity for vertical (An = 0) ionization allows vibrational frequencies of CgHgNH2 ( B,) to be determined Two-colour photoacoustic and MPI spectra of aniline, determined as a function of time delay between the two laser pulses. Observed both ionization and dissociation t MPI/TOF mass spectrometric study of phenol. Mechanism of ionization and ion fragmentation t MPI/TOF mass spectrometric study of fragmentation patterns in benzaldehyde. Strong wavelength dependence observed at 266 and 355 nm. Results show operation of two different mechanisms at these excitation wavelengths... 

When the time delay between excitation and diagnostic electron scattering is 15 ns, only fragmentation and no cis-trans isomerization is observed. When the time delay is several milliseconds, cis-trans isomerization is prevalent. 

Figure 5.77. The gradient-selected INEPT-INADEQUATE sequence for identifying carbon-carbon connectivities through proton observation (time delays in the sequence have been removed for clarity). The sequence selects for H- C- C fragments for which the gradient ratios are 1 —1 1. Despite the complexity of the sequence, its operation may be understood by recognising discrete, simpler segments within it that have defined roles to play, which in this case are INEPT and INADEQUATE steps.

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