Spectrum acquisition time

FT-MS is the slowest among all MS techniques. The long SAT of FT-MS is due to an extended time for acquiring the transient, which is essential for the accurate determination of frequencies of periodic motions of ions. Moreover, FT mass analyzers need to be installed in ultrahigh vacuum environments, and such environments require long ion transmission paths and several differentially pumped vacuum stages. Because commercial FT mass analyzers are installed downstream of IT mass analyzers, the typical SATs of FT-MS range from hundreds of milliseconds to tens of seconds. 

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When IR radiation (0.7 bending motions in the molecule. Thus, by examination of the IR absorption spectrum it is possible to identify the molecular species. Although more selective than MS, FTIR is widely employed in EGA, owing to its relatively high sensitivity and short spectrum acquisition time. The structure... 

Table 3.1 Typical spectrum acquisition time of important types of individual mass analyzers and ion sources that are often combined with these analyzers...

Mass analyzer Spectrum acquisition time (s) Ion sources... 

Figure 5.1 The typical spectrum acquisition times of important types of mass spectrometers...

Relationship between Spectrum Acquisition Time and Mass Spectrometer Performance... 

Prices low enough for the instructional market manufacturers require some compromises in system performance. In some instruments, laser power is less than 10 mW, but others employ 500-mW lasers. Although low laser power lengthens spectrum acquisition time, it also reduces the risk of eye damage to inexperienced operators. 

The first step of operation of AGC is the addition of a pre-scan to the traditional recording sequence of a mass spectrum in an ion trap. The duration of the pre-scan must be short in comparison with the total duration of the sequence to keep the spectrum acquisition time reasonable. The pre-scan starts with an ionization phase of fixed... 

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