Mass spectrometry, FT-ICR

Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR) is a very high-resolution mass spectral method (105 to 106, with mass accuracy better than 1 ppm), which allows separation and empirical formula measurement of potentially thousands of metabolites without chromatic separation. 

Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR)... 

The field of ion-molecule reactions has profited immensely from the introduction of new techniques in mass spectrometry such as Fourier Transform Ion-Cyclotron Resonance Mass Spectrometry (FT-ICR) and Selected-Ion Flow Tube methods (SIFT). Several accounts of the progress in the field of ion-molecule reactions involving silicon-containing molecules have been published. For review articles the reader is referred elsewhere1,3,4,40-51 A detailed compilation of the kinetic data for bimolecular ion-molecule reactions of positive silicon ions has been published by Anicich52. 

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. 

Kujawinski, E. B., Hatcher, P. G., and Freitas, M. A. (2002). High-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of humic and fulvic acids Improvements and comparisons. Anal. Chem. 74,413 119. 

Technological advances of ion-trap mass spectrometers are the ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and the recently released technique, the Orbitrap Fourier transform mass spectrometry (Hu et al., 2005), which enable the determination of molecular formulae with a high mass resolution and mass accuracy in mixtures. Today these ion-trap mass spectrometers are most frequently coupled with atmospheric pressure ionization (API) techniques such as electrospray ionization (ESI) (e.g., Fievre et al., 1997 Qian et al., 2001 Kujawinski et al., 2002 Llewelyn et al., 2002 Stenson et al., 2002,2003 Fard et al., 2003) or matrix-assisted laser desorption/ionization (MALDI) (e.g., Solouki et al.,... 

The quadrupole ion trap is seen as a compact and less expensive alternative to FT-ICR mass spectrometers employed for gas-phase metal ion chemical and mass analysis [28,29]. Although lacking the high mass resolving powers available in Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), the quadrupole ion trap has been investigated by using nonselective and resonance-selective ionization of ablated metal samples. 

The same concept in proteomics studies has technological implications, e.g., which method, sample preparation protocols, and instrumentation will be used. Again, top-down analysis will be based on isolation, analysis, and characterization of an intact protein to reveal its function. Fourier transformed ion cyclotron resonance mass spectrometry (FT-ICR) (Marshall et al., 1998) facilitates such approach in protein identification as a result of random fragmentation of an intact molecule. In contrary, bottom-up approach is based on up-front fragmentation of the protein in question using various proteolytic enzymes with known specificity (Chalmers et al., 2005 Millea et al., 2006). In these experiments, trypsin is most commonly used. An important question that remains is whether more... 

The gas-phase reactions of lanthanide (Ln+ = La+-Lu+, except Pm+) cations with iron pentacarbonyl, Fe(CO)s, and with ferrocene, Cp2Fe, have been studied by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/ MS). In the case of Fe(GO)s, the observed primary products were of the type LnFe(CO)x+ (Ln = La, Ce, Pr, Nd, Gd, Tb v = 3 Ln = Ho, Er, Lu x = 3 and 4 Ln = Sm, Eu, Dy, Tm, Yb x = 4), and evidence was obtained for the presence of direct Ln-Fe bonds in these species. With Cp2Fe the majority of the Ln+ cations reacted by metal exchange, yielding Ln bis(cyclopentadienyl) ions Cp2Ln+, while the less reactive Ln+ cations formed the adduct ions LnFeCp2+.851... 

Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS) instrumentation offers excellent sensitivity, accuracy (<1 ppm), and high mass resolution (>1,000,000) (Table 10.2). However, because of being too expensive, difficult to use, and not compatible with conventional HPLC columns and flow rates, FTMS has not been frequently used in pharmaceutical research. This changed with an introduction of a hybrid instrument consisting of a linear ion-trap mass spectrometer compatible with LC and an ion-cyclotron-resonance (ICR) detector. Such a hybrid instrument is compatible with conventional HPLC and allows for acquisition of accurate mass data-dependent MS" spectra. Sanders et al. [128] recently reviewed the utility of hybrid LTQ-FTMS for drug metabolism and metabonomics applications while Brown et al. [129] reviewed the metabolomics applications of FT-ICR-MS. 

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) for Analysis of Compound Libraries... 

Direct determination of the charge states can also be done by recording the ESI mass spectrum on an instrument that allows for the resolution of the isotope peaks of the analyte. (Chapter 1 in this book discusses mass resolution in greater detail.) Figure 4.4 shows the resolution of isotope peaks, by using ESI and Fourier-transform ion-cyclotron resonance mass spectrometry (FT-ICR) for the multiply charged ion of recombinant human insulin with m/z 1162.53 as a centroid. (The resolving power of the analyzer used to record... 

In the last decade there has been a fast progress in the field of mass spectrometry employing soft ionization techniques such as electrospray ionization mass spectrometry (ESI-MS), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), and matrix-assisted laser desorption ionization mass spectrometry (MALDI)-MS. These tools provide molecular level information on humic substances. 

A wide variety of other MS techniques are used to detect explosives. Two notable techniques are Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and CE-MS. FT-ICR-MS is used to probe pseudomolecular ion formation of RDX, PETN, and TNT using several ionization sources including EDI, El, electron capture ionization (EC), and chemical ionization (Cl). Analyses are performed both in the positive and negative ionization mode, and identities are assigned to the major pseudomolecular ion peaks seen in the spectra from each explosive [198]. TTie composition of several explosive compounds from postblast residue is assessed with FT-ICR-MS by identifying the explosive and inactive ingredients in a smokeless powder, TNT,... 

Rodgers, R.P, Marshall, A.G. (2007) Chapter 3 petro-leomics advanced characterization of petroleum-derived materials by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). In Asphaltenes, Heavy Oils, and Petroleomics, edited by Mullins, O.C., Sheu, E.Y., Hammami, A., Marshall, A.G. New York Springer. 

MS has been used in the characterization of vegetable oils, which are potential feedstocks for FAME production. Catharino et al. [18] and Saraiva et al. [19] used ESI-MS (Q-TOF and MALDI-TOF) and chemometrics on vegetable oils. Wu et al. [23] used ultrahigh-resolution MS (Fourier transform ion cyclotron resonance mass spectrometry [FT-ICR-MS]) in characterization of vegetable oils, with emphasis on structure elucidation where FT-ICR-MS is superior. Catharino et al. [24] used Q-TOF in the characterization of FAME, however, without the use of chemometrics. 

Van der Flage and co-workers [280] combined MALDI and Fourier transform ion cyclotron mass spectrometry (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 m/z 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 [280]. 

Two distinct initiation pathways were observed in the presence of relatively large amounts of thermal initiator, as desaibed above. The smaller peaks at 16 amu higher than all of the main peaks are due to adducts as opposed to Na" adducts. Molecular structures 12 and 13 have predicted molecular masses of 1523.776 (C75Hi2of 3oh ) 2ind 1590.818 (C79Hi2503oh Na), respectively, as compared with 1523.774 and 1590.808 from MALDI-Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Table 1 lists the observed peaks along with their observed and predicted peak heights. 

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