Sector field analysers

In addition to the diversity of ionisation techniques available, mass spectrometers offer a selection of mass analyser configurations. Of note are single (MS) and triple quadrupole (MS—MS) instruments, ion trap analysers (MS)n, time-of-flight (ToF) analysers, sector field analysers, and Fourier transform-ion cyclotron resonance (FTICR) instruments. 

Figure Bl.6.3 Electron energy analysers that use magnetic fields (a) the trochoidal analyser employing an electromagnet, (b) the Wien filter and (c) the sector magnet analyser. Trajectories for electrons of different energies are shown.

A Thermo Finnigan Element 2 Inductively Coupled Plasma Sector-Field Mass Spectrometer (ICP-SF-MS) with guard electrode was employed for trace element analyses. RSD values derived from internal check standard never exceeded 10%. Accuracy was better than 15% for all elements as determined by analyzing the certified reference standard NWRI TM-RAIN 95 trace metal fortified rainwater, every 5 to 8 samples. 

One of the more recent branches of atomic spectrometry, although perhaps the most exciting one, is atomic mass spectrometry, which has had a very important impact on science and technology. At present, atomic mass spectrometry is ordinarily performed using inductively coupled plasma ion sources and either a quadrupole or a scanning sector-field mass spectrometer as an analyser. The remarkable attributes of such a combination, being an indispensable tool for elemental analysis, include ... 

However, nowadays some other different mass spectrometers are used for ICP-MS time-of-flight (TOP) systems for multielemental analysis of transient signals, ion trap analysers for ion storage, multicollector instruments for precise isotope ratio measurements and double-focusing sector field mass spectrometers for high mass resolution, but still the majority of instruments are equipped with quadrupole filters, which are simpler and cheaper. 

Fig. 5 Statistical evaluation of LC-MS-based methods for tropane alkaloids referred in this chapter. (a) Relative frequency of ionization methods. +APCI positive atmospheric pressure chemical ionization, +ESI positive electrospray ionization, FAB fast atom bombardment, +TSP positive thermospray, (b) Relative frequency of scan modes used. MS full scan MS, MS/MS tandem mass spectrometry (product ion scan), MRM multiple reaction monitoring, SIM selected ion monitoring, (c) Relative frequency of mass analysers used. EBQtQ2 double focusing sector field mass spectrometer, IT ion trap, QqQ triple quadrupole, SQ single quadrupole. Considered publications were found by PubMed data-based search and references cited in these articles...

At last, the double focusing sector field mass spectrometer (EBQjQ2) should briefly be addressed. This mass analyser represents a highly sophisticated early design that has rarely been used for routine analysis especially for quantification. For detailed information on the functional principle the reader is referred to respective textbooks on mass spectrometry. We mention this technique as Kajbaf et al. used EBQjQ2 for detection and identification of the QTA cimetropium and its biotransformation products from liver microsomal mixtures in offline analysis of HPLC fractions after FAB ionization [23, 62] (Table 7). 

The mass analyser separates the ionised species according to their mass-to-charge (miz) ratio. This can be achieved by magnetic or electric sector fields, an ion trap. 

Figure 13.9 Principle of electric- and magnetic-sector charged-particle analysers, here shown for a 180° sector (hemispherical analyser). Conceptually, electric sectors serve as kinetic energy analysers magnetic sectors (magnetic field perpendicular to the plane) constitute mass analysers...

Characterisation of ancient and art nouveau glass samples by Pb isotopic analyses using laser ablation coupled to a magnetic sector field inductively coupled plasma mass spectrometer. J. Anal. At. Spectrom.,... 

In the classical mass-spectroscopic detection, the entirety of the gas molecules and atoms of to be analysed atmosphere is first ionised and accelerated. It is done under high vacuum conditions. The ions are separated according to their mass/charge ratio in the magnetic sector field and subsequently detected. 

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