Fourier-transform ion cyclotron mass spectroscopy

Van der Hage and co-workers [147] combined MALDI and Fourier-transform ion cyclotron mass spectroscopy (FT-ICR-MS) for the characterisation of polyoxyalkyleneamines. MALDI FT-ICR-MS was used to resolve intact, sodium ion cationised oligomer ions in the mass range from miz 500 to 3500. NMR was used to measure the average end-group distribution to provide insight into conformational differences. In this respect, FT-ICR-MS and NMR data were complementary. Combined results yielded detailed information about chemical composition distributions of polyalkyleneamines that hitherto it was not possible to obtain with either technique separately. Merits and limitations of the data produced with MALDI-FT-ICR-MS are discussed and compared with those of H- and C-NMR data [147]. 

Van Rooij and co-workers [126] used MALDI on an external ion source Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) to analyse the block length distributions of triblock polymers of poly(oxypropylene) and poly(oxyethylene). For the first time, detailed and accurate molecular weight data were obtained on a complex sample using this methodology, which independently validated the data provided by the manufacturer. The experimentally verified random coupling hypothesis proved the validity of the methodology. 

The first series of results presented demonstrate that the apparent MWD are distorted. This distortion is induced by the flight-time-induced mass discrimination inherent in the experimental technique, the variation of isotopic patterns over the measured mass range, and the overlap of peaks in the spectrum. Subsequently, a method which overcame this difficulty was developed. 

Van Rooij and co-workers [126] were able to determine the MWD of a triblock polymer of polyoxypropylene and polyoxyethylene following the method of O Connor and co-workers [148], which compensates for flight-time-induced mass discriminations during the ion transport from the ion source to the ICR cell. 

---

Several methods exist that allow the determination of the standard enthalpies of formation of the ionic species. The reader is referred to two recent rigorous and detailed chapters by Lias and Bartmess and Ervin. The vast majority of the experimental data reported here are obtained by means of Fourier transform ion cyclotron resonance spectroscopy (FT ICR), high-pressure mass spectrometry (HPMS), selected ion flow tube (SIFT), and pulsed-field ionization (PFI) techniques, particularly pulsed-field ionization photoelectron photoion coincidence (PFI-PEPICO). All these experimental techniques have been examined quite recently, respectively, by Marshall, Kebarle, B6hme," ° Ng" and Baer. These chapters appear in a single (remarkable) issue of the International Journal of Mass Spectrometry. An excellent independent discussion of the thermochemical data of ions, with a careful survey of these and other experimental methods, is given in Ref. 37. 

Comisarow M B and Marshall A G 1996 Early development of Fourier transform ion cyclotron resonance (FT-ICR) spectroscopy J. Mass Spectrom. 31 581-5... 

Fourier transform ion cyclotron resonance mass spectrometry (FTIC-MS), 155 of ionic clusters, 172-173 FTIR spectroscopy, 191-192... 

Comisarow, M.B. Marshall, A.G. The Early Development of Fourier Transform Ion Cyclotron Resonance (FT-ICR) Spectroscopy. J. Mass Spectrom. 1996, 37,581-585. 

Attempts have been made to observe and experimentally determine the structure of CH5+ in the gas phase and study it in the condensed state using IR spectroscopy,764 765 pulse electron-beam mass spectrometry,766 and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS).767 However, an unambiguous structure determination was unsuccessful. Retardation of the degenerate rearrangement was achieved by trapping the ion in clusters with H2, CH4, Ar, or N2. 

Tremblay, L. B., Dittmar,T., Marshall, A. G., Cooper, W. J., and Cooper, W.T. (2007). Molecular characterization of dissolved organic matter in a North Brazilian mangrove porewater and mangrove-fringed estuaries by ultrahigh resolution Fourier transform-ion cyclotron resonance mass spectrometry and excitation/emission spectroscopy. Marine Chem. 105, 15-29. 

Many heterocycles, for instance NH-azoles, have acid-base properties of either or both proton gain (basicity) and proton loss (acidity) [85], The possibility of studying such processes in the gas-phase (mass spectrometry and Fourier transform ion cyclotron resonance - FTICR - spectroscopy) provides theoreticians with values... 

Owing to its stability, solubility, and highly reproducible oxidation behavior, ferrocene has long been used as an electrochemical standard in nonaqueous solvents. Not surprisingly, the electron-donor or -acceptor properties of ring substituents in ferrocenes and other metallocenes have been repeatedly evaluated with electrochemical techniques. Measurements have been obtained using polarography,150 cyclic voltammetry (CV),151 chronopotentiometry,152 photoelectron spectroscopy, 53 and Fourier transform ion cyclotron resonance mass spectrometry.154 Extensive compilations of such data are available.155 156 Historically, variations of oxidation potentials have been discussed almost solely in terms of the... 

The next important quantity is the interaction energy, which may be obtained experimentally through the measurement of association or complexation constants K (for instance, via Fourier-Transform Ion Cyclotron Resonance mass spectrometry or Nuclear Magnetic Resonance (NMR) spectroscopy see also the other chapters in this volume) that are related to the total free enthalpy change AG of the host-guest complexation through... 

All of this chemistry occurs in either solution or the solid state and is often influenced by the presence of a solvent. Currently, the tools of modern chemical physics are used to try to understand metal-ligand chemistry in the gas phase, free from the effects of solvents. The focus has been on understanding the chemistry, photochemistry, and spectroscopy of relatively small systems. For reasons of sensitivity, the primary tool for these investigations is the mass spectrometer. Sometimes lasers are used to vaporize a metal or to excite and to ionize the species of interest. The experimental techniques range from traditional high-pressure mass spectrometry to Fourier transform ion cyclotron resonance. 

Various forms of tandem mass spectroscopy (MS/MS) have also been used in the analysis of biomolecules. Such instruments consist of an ionisation source (ESI or MALDI or other) attached to a first mass analyser followed by a gas-phase collision cell. This collison cell further fragments the selected ions and feeds these ions to a second mass detector. The final mass spectrum represents a ladder of fragment ions. In the case of peptides the collision cell usually cleaves the peptides at the amide bond. The ladder of resulting peptides reveals the sequence directly [496]. Thus, tandem MS instruments, such as the triple quadrupole and ion-trap instruments have been routinely applied in LC-MS/MS or ESI-MS/MS for peptide sequencing and protein identification via database searching. New configurations, which have been moving into this area include the hybrid Q-TOF [498], the MALDI-TOF-TOF [499] and the Fourier transform ion cyclotron resonance instruments [500]. 

In a series of studies Bickelhaupt et al. [64, 87, 88] investigated base-induced elimination reactions experimentally with Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectroscopy and theoretically with DF calculations. They applied the computational scheme of Baerends et al. [5], using the gradient corrections of Becke [89] for the exchange potential. They studied the fundamental class of reactions... 

Fig. 5 Fourier-Transform Ion Cyclotron Resonance (FTICR) mass spectrometer with electrospray ionization (ESI) source used for IRMPD ion spectroscopy at the FELIX facility. The hexapole ion guide is also used to accumulate ions from the ESI source before being pulse-injected into the ICR ceil. The inside of the excite electrodes of the ICR cell are polished so that they act as a multipass reflection ceil for the IR beam fiom FELIX (or an OPO) achieving approximately 10 passes through the ion cloud. Adapted from [142]...

Fig. 1 Infrared photodissociation action spectra in the fingerprint infrared region Irom fairly early in the modem evolution of spectroscopy of biologically interesting complex ions. These spectra illustrate the use of electrospray ion production, ion trapping mass spectrometry (Fourier-transform ion cyclotron resonance in these examples) and the FELIX free electron laser light source. Lower spectrum originally derived from [10, 11] middle spectrum frran [12] upper spectrum from [13]. Figure reproduced with permission from [12]...

---