Ion cyclotron resonance mass spectra

Stenson, A. C., Marshall, A. G., and Cooper, W.T. (2003). Exact masses and chemical formulas of individual Suwannee River fulvic acids from ultrahigh resolution electrospray ionization fourier transform ion cyclotron resonance mass spectra. Anal. Chem. 75,1275-1284. 

Table 3.1. Chemical formulas from exact masses in electrospray ionization Fourier-transform ion cyclotron resonance mass spectra (adapted from Fievre etal., 1997).

Fig. 3.12. Series of electrospray ionization Fourier-transform ion cyclotron resonance mass spectra obtained in a two-dimensional mass spectrometry experiment. Proceeding from top to bottom (a) full mass spectrum of a fulvic acid mixture (b) stored waveform inverse Fourier transform (SWIFT) waveform ejection from the ion cyclotron resonance cell of ions of all but a narrow m/z range (c) the resulting isolated parent ion mass spectrum and (d) the product ion mass spectra produced by collision-induced dissociation. Reprinted from Fievre etal. (1997) with permission from the American Chemical Society.

Fig. 3.20. Electrospray ion cyclotron resonance mass spectra of dissolved organic matter isolated from Experimental Nutrient Removal (ENR) wetland outflow before (top) and after (bottom) selective organic phosphorus concentration. Reprinted from Llewelyn etal. (2002) with permission from the American Chemical Society.

Resolution Electrospray Fourier Transform-Ion Cyclotron Resonance Mass Spectra. Int. J. Mass Spectrom. 2005, 246, 1-9. 

Fig. 11.14 Tetrahenzoxazines (/f)-3 and (S)-3 and tetrakis-aminomethylated Fesoicinarene (S)-17. Quaternary ammonium ions (18). Isotope pattern regions of the ESI-PTlCR (FTICR Fourier transform ion cyclotron resonance) mass spectra of (S)-17 with pseudo-racemates of the two guests. The bottom row represents control experiments with a reversed labelling of the two guest enantiomers as compared to the top row [35] (Image reproduced frinn [35] with permission from Springer)...

In analyses where molecular masses are being matched, more accurate mass measurements provide more reliable matches and identifications.26,65,66 In a reference laboratory the mass accuracy to several decimal points, provided by a Fourier transform ion cyclotron resonance mass analyzer, may be desirable. In field or portable systems there is usually a trade-off in mass accuracy for size and ruggedness. Reliable identifications can be made with moderate mass accuracy, even 1 Da, if a large enough suite of molecular ions is recorded and used to search the database. If both positive ion and negative ion spectra are... 

The highest-resolution mass spectra are obtained by Fourier transform ion cyclotron resonance mass spectrometry.34 Molecular ions of two peptides (chains of seven amino acids) differing in mass by 0.000 45 Da were separated with a 10% valley between them. The ions each have a mass of 906.49 Da and a width at half-height of 0.000 27 Da. Compute the resolving power by the 10% valley formula and by the half-width formula. Compare the difference in mass of these two compounds with the mass of an electron. 

Thus the interpretation of ESI-MS spectra of POPAM dendrimers recorded on an FT-ICR (Fourier-Transform Ion Cyclotron Resonance) mass spectrometer leads to drastic overestimation of defects in the sample molecules (Fig. 7.4). The... 

The negative ion mass spectra of 21 was studied by an electron im-pact/Fourier transform ion cyclotron resonance mass spectrometry method (95MI13). 

The instrumentation employed by Stapleton and Bowie was an ion cyclotron resonance mass spectrometer that had been modified to permit computer control of all drift voltages and to allow direct reading of the ion transit time (typically 10 to 10 seconds) similar to that described by McMahon and Beauchamp An emission current of about 0.2 microampere and a nominal 70 eV electron beam produced ion currents of 10 to 10 A at source pressures of approximately 10 Torr. The mass spectra were measured by magnetic field modulation. 

Given the complexity of the oligonucleotide MS and MS-MS spectra, the application of high-resolntion instmments like Fonrier-transform ion-cyclotron resonance mass spectrometers (FT-ICR-MS) is beneficial. While some initial results were reported in the mid-1990s, e.g., [37-38], the fieqnent ntilization of FT-ICR-MS in oligonucleotide characterization is more recent (Ch. 22.3.3). 

Hogan, J. D. and Laude, D. A. J., "Mass Discrimination in Laser Desorption/ Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Cation-Attachment Spectra of Polymers," Anal. Chem., 64, 763-769, 1992. 

All mass spectra were obtained with a Fourier transform ion cyclotron resonance mass spectrometer (FTMS). The theory and applications of FTMS spectrometry are well-established and will not be discussed here. In our apparatus the sample was located at one of the trap plates of the cell, inside a superconducting magnet. Two pulsed lasers were used, one for tire PFPE desorption and another for metal ion formation. Typically, 2 to 4 mj/pulse of 248 nm or 193-nm light (20 ns fwhm) from an excimer laser was softly focused to an elliptical spot with a 2-mm long axis for desorption. To create the metal ions, a 0.3-mJ pulse of 532-nm light (10 ns fwhm) from the doubled output of a Nd YAG was tightly focused. The metal substrates were prepared from foils of various metals (typically 0.010 in. tiiick). Surface preparation was not critical because the experiment was not sensitive to PFPE/metal surface interactions since the thickness of the polymer films was on the order of 1 pm. 

VaUe, J.J. Eyler, J.R. Oomens, J. Moore, D.T. van der Meer, A.F.G. von Helden, G. Meijer, G. Hendrickson, C.L. Marshall, A.G. Blakney, G.T. Free electron laser-Fourier transform ion cyclotron resonance mass spectrometry facility for obtaining infrared multiphoton dissociation spectra of gaseous ions. Rev. Sci. Instrum. 2005, 76.023103. 

Figure 1 Comparison of parts of the SORI-CAD ESI FT-ICR mass spectra of the [M + 3 H] + precursor ions of (A) nisin A (wild-type nisin), (B) nisin S5A, (C) nisin H27 K, and (D) nisin I30W-H, showing the region containing doubly charged fragment ions. The ions in the transgenic variants that are shifted in mass compared to nisin A are marked with asterisks. (Reprinted from Lavanant H, Heck A, Derrick PJ, et al. (1998) Characterization of genetically modified nisin molecules by Fourier transform ion cyclotron resonance mass spectrometry. European IVIass Spectrometry 4-. 405-416, with permission IM Publications.)...

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,... 

All films were free from cracks and defects and thick enough for laser desorption ionization-Fourier transform ion cyclotron resonance-mass spectrometry (LDI-FTICR-MS) spectra to be rid of the silicon signal (Si-H at mass-to-charge ratio [m/z] = 28). 

Valle JJ, Eyler JR, Oomens J, Moore DT, van der Meer AFG, von Helden G, Meijer G, Hendrickson CL, Marshall AG, Blakney G (2005) free electron laser-Foniier transform ion cyclotron resonance mass spectrometry facility for obtaining infinred multiphoton dissociation spectra of gaseous ions. Rev Sci Instrum 76 023103... 

To check the identity and purity of the products obtained in the above reactions it is not sufficient to analyze for the sulfur content since a mixture may incidentally have the same S content. Either X-ray diffraction on single crystals or Raman spectra of powder-like or crystalline samples will help to identify the anion(s) present in the product. However, the most convincing information comes from laser desorption Fourier transform ion cyclotron resonance (FTICR) mass spectra in the negative ion mode (LD mass spectra). It has been demonstrated that pure samples of K2S3 and K2S5 show peaks originating from S radical anions which are of the same size as the dianions in the particular sample no fragment ions of this type were observed [28]. 

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