Analyzer mass ranges achievable with

Accurate mass measurement requires high resolving power. The difference in degrees of difficulty between measuring an m/z of 28 and one of 28.000 is likely to be large. Table 39.3 shows the broad mass ranges achievable with various analyzers. 

Typical Mass Ranges Achievable with Various Analyzers... 

An added consideration is that the TOF instruments are easily and quickly calibrated. As the mass range increases again (m/z 5,000-50,000), magnetic-sector instruments (with added electric sector) and ion cyclotron resonance instruments are very effective, but their prices tend to match the increases in resolving powers. At the top end of these ranges, masses of several million have been analyzed by using Fourier-transform ion cyclotron resonance (FTICR) instruments, but such measurements tend to be isolated rather than targets that can be achieved in everyday use. 

A mass calibration for FTICR analyzers with superconducting magnets is very stable and is valid for many days for normal applications. Mass accuracy < 1 ppm can be obtained over a fairly wide mass range. Unique elemental composition can be determined for masses over 800 Da [262]. Recently, 0.1 ppm mass accuracy, which required a mass resolving power >300,000, has been achieved for several thousand peaks by a 14.5 T instrument [263] and commercial instruments with mass accuracy <0.2 ppm are available. As with the orbitrap (see Section 2.2.5) the frequency is... 

Typical residual gas analyzers employ electron impact to generate ions and a quadrupole mass filter to obtain the mass-to-charge ratio of these species. Mass ranges for these analyzers vary 2-80 atomic mass units for small units 1-500 on larger, more expensive gas analyzers. Electron impact ionization of the gas is achieved using a hot filament as the source. Many instruments are equipped with a second filament which can be switched into use in the event of a failure of the first. When a robust detector of moderate sensitivity is needed, a... 

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