Tandem quadrupole

Tandem quadrupole and magnetic-sector mass spectrometers as well as FT-ICR and ion trap instruments have been employed in MS/MS experiments involving precursor/product/neutral relationships. Fragmentation can be the result of a metastable decomposition or collision-induced dissociation (CID). The purpose of this type of instrumentation is to identify, qualitatively or quantitatively, specific compounds contained in complex mixtures. This method provides high sensitivity and high specificity. The instrumentation commonly applied in GC/MS is discussed under the MS/MS Instrumentation heading, which appears earlier in this chapter. 

Figure 5.45 Structures of (1) Bosentan (C27H29N5O6S [M + H]+ 552.1917) and three of its metabolites, formed by (2) oxidation (C27H29N5O7S [M + H]+ 568.1866), (3) demethylation (C26H27N5O6S [M- -H]+ 538.1760), and (4) demethylation-oxidation (C26H27N5O7S [M + M]+ 554.1709). Reprinted by permission of Elsevier Science from Exact mass measurement of product ions for the structural elucidation of drug metabolites with a tandem quadrupole orthogonal-acceleration time-of-flight mass spectrometer , by Hopfgartner, G., Chemushevich, I. V., Covey, T., Plomley, 1. B. and Bonner, R., Journal of the American Society for Mass Spectrometry, Vol. 10, pp. 1305-1314, Copyright 1999 by the American Society for Mass Spectrometry.

Several other interface designs were introduced over this period, including continuous flow fast atom bombardment (CFFAB)" and the particle beam interface (PBI)," but it was not until the introduction of the API source that LC/MS applications really came to the forefront for quantitative analysis. Early work by Muck and Henion proved the utility of an atmospheric pressure interface using a tandem quadrupole mass spectrometer. 

It should be pointed out that FAB, MALDI, and ESI can be used to provide ions for peptide mass maps or for microsequencing and that any kind of ion analyzer can support searches based only on molecular masses. Fragment or sequence ions are provided by instruments that can both select precursor ions and record their fragmentation. Such mass spectrometers include ion traps, Fourier transform ion cyclotron resonance, tandem quadrupole, tandem magnetic sector, several configurations of time-of-flight (TOF) analyzers, and hybrid systems such as quadrupole-TOF and ion trap-TOF analyzers. 

Loboda A.V., Krutchinsky A.N., Bromisrski M., Ens W., and Standing K.G. (2000), A tandem quadrupole/time of flight mass spectrometer with a matrix-assisted laser desorption/ionization source design and performance, Rapid Commun. Mass Spectrom. 14, 1047-1057. 

Yost, R.A. Enke, C.G. Selected Ion Fragmentation With a Tandem Quadrupole Mass Spectrometer. J. Am. Chem. Soc. 1978,100, 2274-2275. 

Hvattum, E. and Ekeberg, D., Study of the collision-induced radical cleavage of flavonoid glycosides using negative electrospray ionization tandem quadrupole mass spectrometry, J. Mass Spectrom., 38, 43, 2003. 

These are not the only types of tandem mass spectrometers. There are numerous configurations of instruments that are based on the type of ion separation and many new terms associated with these instrument types. For example, there are instruments known as ion traps. The ion trap is a device that can measure mass, fragment a selected mass (as could be done in a collision cell) and then measure the mass of the fragment. The product ion produced by this all in one device is the same product ion that would be produced in a tandem quadrupole instrument. However, there is only one mass analyzer that functions as both the collision cell and mass measuring device. These types of instruments are sometimes referred to as tandem mass spectrometers, but are not abbreviated as MS/MS. The MS/MS analysis is done by separating the analysis in time (tandem in time) rather than two devices separated in space. A more generic term is best suited. This term is MS , where the n represents... 

Nassar, A. E. (2003). Online hydrogen-deuterium exchange and a tandem-quadrupole time-of-flight mass spectrometer coupled with liquid chromatography for metabolite identification in drug metabolism. J. Chromatogr. Sci. 41 398-404. 

Common tandem-in-space instruments employ a quadrupole as the first mass analyzer, a multipole collision cell (usually hexapole) operated in RF-only mode, and then either a second quadrupole or a TOF tube as the second mass analyzer. These instruments are termed triple or tandem quadrupole and quadrupole-time-of-flight mass spectrometers. 

There are three MS/MS experiments that are of use in carbohydrate analysis. These can be depicted schematically (Fig. 11) and are described using a tandem quadrupole instrument as an example. Quadrupole-based tandem-in-space instruments operate at low CID energies (up to 100-200 eV). 

The latter two experiments can be best performed on a tandem quadrupole instrument, although software data manipulation can allow this type of data to be extracted from experiments on other instruments. 

As noted earlier, the development of the dual cell (37), tandem quadrupole-FTMS (46, 47) and external ionization cell (48, 49) has facilitated the coupling of FTMS and chromatographic methods. Advances in interfacing separation techniques with FTMS will be important in the analysis of mixtures, especially where high mass resolution is required. For example, liquid chromatographic introduction of mixtures isolated from biological systems directly into an FTMS for analysis would eliminate the need for laborious sample clean up. 

D. F. Hunt, J. Shabanowitz, R. T. Mclver, Jr., R. L. Hunter, and J. E. P. Syka, "Ionization and Mass Analysis of Nonvolatile Compounds by Particle Bombardment Tandem-Quadrupole Fourier Transform Mass Spectrometry," Anal. Chem., 57, 765-768 (1985). 

Tandem Quadrupole FTMS Use of a quadrupole mass filter for... 

Hopfgartner, G. Chernushevich, I. Covey, T. Bonner, R. 1998. Exact mass measurements on product ions for structural elucidation of drug metabolites with a tandem quadrupole TOF instrument. Proc. 46th ASMS Conf. Mass Spectrom. and Allied Topics (Orlando, Florida), 713. 

McCurvin DMA, Schellenberg DH, Clement RE, et al. 1989. A comparison of tandem quadrupole mass spectrometry versus single quadrupole capabilities for the determination of chlorinated dioxins and dibenzofiirans in environmental samples. Chemosphere 19 201-204. 

Reiner EJ, Schellenberg DH, Taguchi VY, et al. 1990. Application of tandem quadrupole mass spectrometry for the ultra-trace determination of polychlorinated dibenzo-p-dioxins and dibenzofurans. Chemosphere 20 1385-1392. 

Kaufmann A, Butcher P, Maden K, Widmer M, Giles K, Uria D (2009) Are liquid chromatog-raphy/electrospray tandem quadrupole fragmentation ratios unequivocal confirmation criteria Rapid Commun Mass Spectrom 23 985-998... 

Figure 4. Effects of ion kinetic energy on the MS/MS of 5-indanol (a) MS/MS obtained on MIKES instrument with 7000 eV translational energy (b) spectrum obtained on hybrid BQ (magnet followed by quadrupole) mass spectrometer 95 eV (c) spectrum obtained with QQ (tandem quadrupole) mass spectrometer at 35 eV...

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