Sector analysers

Magnetic sector mass spectrometers accelerate ions to more than 100 times the kinetic energy of ions analysed in quadrupole and ion trap mass spectrometers. The higher accelerating voltage contributes to the fact that ion source contamination is less likely to result in degraded sensitivity. This is particularly important for analysis that requires stable quantitative accuracy. 

The main characteristics of sector mass spectrometers are shown in Table 6.29. Magnetic sector mass spectrometers are often considered more difficult to operate than QMS and ToF-MS the high-voltage source is more demanding to chromatographic interfacing. For figures of merit, see Table 6.27. 

Various tandem MS instrument configurations have been developed, e.g. sector instruments, such as CBCE, CBCECB or CECBCE, and hybrid instruments, e.g. BCECQQ (B = magnetic sector analyser, E = electrostatic analyser, C = collision cell, Q = quadrupole mass spectrometer), all with specific performance. Sector mass spectrometers have been reviewed [168], 

Applications Sector instruments are applied for niche applications such as high-resolution measurements and fundamental ion chemistry studies. Magnetic sector mass spectrometers remain the instrument of choice in areas of target compound trace analysis, accurate mass measurement and isotope ratio measurement. 

Polymer/additive analysis greatly benefits from high-resolution mass data, which often leads to unambiguous identification of (known) additives. However, the investment and operating costs of this instrument do not easily justify its (exclusive) use for the purpose of routine polymer/additive analysis. Analysis of organic polymer additives by means of mass spectrometry is aided by the utilisation of precursor ion and second-generation product ion (MS3) scanning experiments [169], A four-sector 

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Double-focusing mass spectrometer A mass spectrometer consisting of electrostatic and magnetic sector analysers capable of achieving high-mass spectral resolution. 

E, ESA Electric sector analyser, electrostatic ESA Electrostatic analyser... 

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. 

If it is desired to measure the angular distribution parameter / , the experimental set-up of Fig. 1.17 can be used. A rotation of the sector-analyser around the photon beam direction keeps = 90°, but changes the angle or, equivalently, 4>. This set-up has the advantage that the analyser always views the same source volume, independent of the angle 4>. The angle-dependent intensity 7exp of detected electrons, equ. (1.53), then reduces to... 

Figure 1.17 An experimental set-up for electron spectrometry with synchrotron radiation which is well suited to angle-resolved measurements. A double-sector analyser and a monitor analyser are placed in a plane perpendicular to the direction of the photon beam and view the source volume Q. The double-sector analyser can be rotated around the direction of the photon beam thus changing the angle between the setting of the analyser and the electric field vector of linearly polarized incident photons. In this way an angle-dependent intensity as described by equ. (1.55a) can be recorded. The monitor analyser is at a fixed position in space and is used to provide a reference signal against which the signals from the rotatable analyser can be normalized. For all three analysers the trajectories of accepted electrons are indicated by the black areas which go from the source volume Q to the respective channeltron detectors. Reprinted from Nucl. Instr. Meth., A260, Derenbach et al, 258 (1987) with kind permission of Elsevier Science—NL, Sara Burgerhartstraat 25, 1055 KV Amsterdam, The Netherlands.

Figure 4.1 Electrostatic deflection analysers with finite entrance (and exit) slits (sector analysers). The diagrams show the field-defining elements which give these analysers their names, the entrance and exit slits, and one principal trajectory which represents the mean trajectory of electrons from the source through the analyser towards the...

Quadrupole Uses oscillating (DC) electrical fields to selectively stabilize (or destabilize) ions passing through a radiofrequency (RF) quadmpole field. Notably, by varying RF it is possible to select for single mass-to-charge ratio values as all other ions will be lost. This type of mass analyser can accommodate higher gas phase pressures than sector analysers and is often interfaced with GC or HPLC. 

Double focusing magnetic sector analysers use two successive separations, first electrostatic, which separates species on the basis of charge, and then magnetic analysis for mass separation the combined separation is thus made on the basis of the m/z ratio. 

Figure 20 Profile of zero-loss ELS peak using magnetic-sector analyser Figure 4) showing 280 meV resolution at 100 keV primary energy...

The procedure applied to calculate expected CO2 emission needs in 2005-2007 was the same in each of the fourteen sectors analysed ... 

Multiplying the CO2 emission change indexes by base emissions created the CO2 emission needs in each of the sectors analysed. The results are shown in Table 12.6. Emission needs in 2005-2007 are about 20% higher than base emissions from 1999-2002. 

For decades, the most widely used mass spectrometers employed magnetic sector analysers for sorting ions by mass, or more correctly, mass-to-charge ratio, commonly referred to as m/z. Magnetic sectors use a magnetic field to deflect the trajectory of... 

Magnetic sector analysers are considered to be medium-resolution instruments with f <2000. They are also an important component in the high-resolution double-focusing spectrometers discussed next. 

The development of a method for cross-sector analyses faces several challenges, for example, system complexity and infrastmcture interdependencies. Interdependencies create entanglements that, depending on the situation, may cause shocks in various societal functions. Even though some recent approaches exist (e.g., (Johansson and Jonsson 2008 Kroger 2008)), few if any, are explicitly integrated into the RVA. 

Rinaldi et al. (2001) and BalduceUi et al. (2005) point out the challenges related to developing extensive architectures and frameworks for modeling and simulating dependencies in infrastructures. There exist many models and computer simulation tools for one infrastructure (e.g., traffic models, electric power load models), but none of these does cross sector analyses. Such models require new computerized tools, access to extensive amounts of data, and integration of the dynamic interplay between the infrastructure models. 

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