Magnetic sector analysers

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

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],... 

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. 

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...

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. 

High energy CID, if the first mass analyser is a magnetic sector analyser. The primary ion has then an energy of several keV. 

This home-built instrument [6] consists of two magnetic sector analysers with a collision cell located in the region between the two analysers. The first stage consists of a Varian MAT CH7 analyser (90 , 21.4 cm radius), and the second stage is a home built 90 , 10.2 cm radius analyser. The precursor ion beam is monitored by the off-line electron multiplier detector No. 1. A voltage of 30 V applied to the deflection... 

Magnetic mass analyser. Where high mass resolution is a requirement in the SIMS experiment, then the traditional magnetic-sector analyser may be utilised. Presently, however, these magnetic mass analysers are used in the DSIMS mode of characterisation. The transmission of secondary ions is much higher than in the quadrupole system, approximately 1%. Due to its lack of usage within the SSIMS area it will not be described further. 

Figure 2.181 Comparison of the resolution power R obtained from quadrupole/ion trap and magnetic sector analysers.

Figure 2.195 High resolution magnetic sector analyser, mass resolution at 10000 at 10% valley (TCDD isotope pattern).

Figure 2.244 Exponential mass calibration of the magnetic sector analyser.

The first hyphenated approach to be considered is the on-line combination of MS and MS, i.e. tandem mass spectrometry (MS-MS). A variety of combinations of different mass analysers have been described, including quadrupole and magnetic-sector analysers as MS], and quadrupole, magnetic-sector, ion-trap and time-of-flight analysers as MS2. Instruments like triple-quadrupoles are widely used for MS-MS, either as stand-alone systems with sample introduction via a solids insertion probe or flow-injection analysis, or in on-line combination with GC or LC. The work of Yost and co-workers and of Hunt and colleagues exemplify these methods. 

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