Magnetic sector analyzer operating modes

Most mass analyzers operate under high-vacuum conditions to ensure that charged particles do not deviate from their trajectories due to collision with residual gas. Mass spectrometers can be grouped into different types of operation mode continuous mode (magnetic sector, quadrupole), pulsed mode (time of flight), and ion trapping mode (quadrupole traps, Fourier transform ion cyclotron, orbitrap). 

The most common modes of operation for ms/ms systems include daughter scan, parent ion scan, neutral loss scan, and selected reaction monitoring. The mode chosen depends on the information required. Stmctural identification is generally obtained using daughter or parent ion scan. The mass analyzers commonly used in tandem systems include quadmpole, magnetic-sector, electric-sector, time-of-flight, and ion cyclotron resonance. Some instmments add a third analyzer such as the triple quadmpole ms (27). 

The operation of magnetic sector (Chap. 4.3), linear quadrupole (Chap. 4.4), or quadrupole ion trap (Chap. 4.5) mass spectrometers in the repetitive scanning mode is useful for the identification of the components of a mixture. If quantitation is a major issue (below), selected ion monitoring (SIM) is preferably employed the term multiple ion detection (MID) and some others are also in use. [33] In the SIM mode, the mass analyzer is operated in a way that it alternately acquires only the ionic masses of interest, i.e. it jumps from one m/z value to the next. [34-39] The information obtained from a SIM trace is equivalent to that from a RIC, but no mass spectra are recorded. Thus, the scan time spent on a diagnostically useless m/z range is almost reduced to zero, whereas the detector time for the ions of interest is increased by a factor of 10-100. [40] An analogous improvement in sensitivity (Chap. 5.2.3) is also observed. 

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