Magnetic-Sector Mass Spectrometry

Chapman, J.R. Gallagher, R.T. Barton, E.C. Curtis, J.M. Derrick, P.J. Advantages of High-Resolution and High-Mass Range Magnetic-Sector Mass Spectrometry for ESI. Org. Mass Spectrom. 1992, 27,195-203. 

A similar technique applicable to reverse geometry mass spectrometers (magnetic sector before electrostatic analyser) is that of mass-analysed ion kinetic energy spectrometry (MIKES). In this technique the ion to be studied is isolated by the magnet and induced to fragment by collision activation in a small chamber filled with a gas such as helium. The product ions are then detected by scanning the electrostatic analyser voltage. 

Fig. 120. Glow discharge mass spectrometry. A Sector field based instrument (a) glow discharge source (b) magnetic sector field (c) electrostatic energy analyzer (d) Daly detector (e) ...

JR Chapman, RT Gallagher, EC Barton, JM Curtis, PJ Derrick. Advantages of high-resolution and high-mass range magnetic-sector mass spectrometry for electrospray ionization. Org Mass Spectrom 27 195, 1992. 

Before ehding this presentation on mass spectrometry, we should cite the existence of spectrometers for which the method of sorting ions coming from the source is different from the magnetic sector. These are mainly quadripolar analyzers and, to a lesser degree, analyzers measuring the ion s time of flight. 

An AutoSpec-TOF mass spectrometer has a magnetic sector and an electron multiplier ion detector for carrying out one type of mass spectrometry plus a TOF analyzer with a microchannel plate multipoint ion collector for another type of mass spectrometry. Either analyzer can be used separately, or the two can be run in tandem (Figure 20.4). 

Note that in mass spectrometry/mass spectrometry (MS/MS) applications, quadrupole and magnetic sectors can be used together advantageously. It is also worth noting that the quadrapole can be operated without the DC voltages. In this RF-only mode, no mass separation occurs, and these quadrapoles are used as ion transmission guides, described in Chapter 49. 

Linked Scanning and Metastable Ions in Magnetic-Sector Mass Spectrometry... 

In conventional mass spectrometry with electric and magnetic sectors arranged in-hne (see Chapter 26), an ion beam consists of a stream of ions of all m/z values, which is separated into individual m/z values by the magnetic sector before being collected by single-point or multipoint detectors (see Chapters 28 and 29). 

Secondary Ion Mass Spectrometry Dynamic Secondary Ion Mass Spectrometry Static Secondary Ion Mass Spectrometry SIMS using a Quadruple Mass Spectrometer SIMS usii a Magnetic Sector Mass Spectrometer See Magnetic SIMS... 

Mass Spectrometry of Small Molecules Magnetic-Sector Instruments 409... 

Luo X, Rehkamper M, Lee D-C, Halliday AN (1997) High precision °Th/ Th and " U/ U measurements using energy-filtered ICP magnetic sector mrrltiple collector mass spectrometry. Inti J Mass Spectrom Ion Processes 171 105-117... 

Shen C-C, Edwards RL, Cheng H, Dorale JA, Thomas RB, Moran SB, Weinstein S, Edmonds HN (2002) Uranium and thorium isotopic and concentration measurements by magnetic sector inductively coupled plasma mass spectrometry. Chem Geol 185 165-178 Shen GT, Dunbar RB (1995) Environmental controls on uranium in reef corals. Geochim Cosmochim Acta 59 2009-2024... 

Different mass analysers can be combined with the electrospray ionization source to effect analysis. These include magnetic sector analysers, quadrupole filter (Q), quadrupole ion trap (QIT), time of flight (TOF), and more recently the Fourrier transform ion cyclotron resonance (FTICR) mass analysers. Tandem mass spectrometry can also be effected by combining one or more mass analysers in tandem, as in a triple quadrupole or a QTOF. The first analyzer is usually used as a mass filter to select parent ions that can be fragmented and analyzed by subsequent analysers. 

R. S. Bordoli, K. Howes, R. G. Vickers, R. H. Bateman, and D. J. Harvey. Matrix-Assisted Laser Desorption Mass Spectrometry on a Magnetic Sector Instrument Fitted with an Array Detector. Rapid Commun. Mass Spectrom., 8(1994) 585-589. 

Isotopic mass spectrometry is used to establish 813C values. The sample is burned to C02 and the intensities of the ion peaks of m/z 44, 45, and 46 are measured. Then correction to eliminate the influence of 170 isotope is achieved. If using sector magnetic instrument and three detectors (for each mass) the standard deviation of the results will be better than 0.001%. The high accuracy of the measurements allows valuable results to be obtained. The ancient Europeans and Americans may be distinguished by the analysis of their remnants. The reason involves the fact that wheat constituted the basic food ration in Europe, while com played the same role in America. The difference in the isotopic composition of these plants forms several units of 813C scale [34],... 

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