Mass spectrometer performances

All mass spectrometers can determine the mjz ratio up to a maximum value. The greatest mass, in Daltons, will depend on the number of charges z that the ion carries, e.g. if the spectrometer is able to measure m/z up to 2000, it will be possible to detect an ion of mass SOkDa carrying 40 elementary charges ( = 40e). 

The sensitivity of a mass spectrometer is given by the weight of sample consumed per second (e.g. a few pg/s or femtomole/s) in order to obtain a signal of normalized intensity. Since the ion beam persists only a very short time, there is a permanent and dynamic renewal of the ions spectra are obtained by repetitive scanning. 

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Syka, J. E. P. Marto, J. A. Bai, D. L. Homing, S. Senko, M. W Schwartz, J. C. Ueberheide, B. Garcia, B. Busby, S. Muratore, T Shabanowitz, J. Hunt, D. F. Novel linear quadmpole ion trap/FT mass spectrometer performance characterization and use in the comparative analysis of histone H3 post-translational modifications. 

MALDI Triple-Quadrupole Mass Spectrometer Performance 350... 

MALDI TRIPLE-QUADRUPOLE MASS SPECTROMETER PERFORMANCE... 

In contrast to QqQ systems, IT mass spectrometers perform sequential ion trapping, isolation of precursor ions and subsequent mass scanning in a single small assembly (ion trap) making this system robust and valuable. 

The Sr/ Sr ratios of calcite and dolomite in 12 samples were determined after washing the samples with distilled water to remove the pore salts that result from drying. The calcite samples were then reacted with dilute acetic acid and the dolomite samples with 0.1 HCl, and analysed using an automated Finnigan 261 mass spectrometer equipped with nine Faraday collectors. All analyses were performed in the static multicollector mode using rhenium filaments. Correction for isotope fractionation during the analysis was made by normalization to Sr/ Sr = 0.1194. The mean standard error of mass spectrometer performance was 0.00003 forNBS-987. 

Syka JEP, Marto JA, Bai DL, Homing S, Senko MW, Schwartz JC, Ueberheide B, Garcia B, Busby S, Muratore T, Shabanowitz J, Hunt DF. Novel linear quadrapole ion trap/FT mass spectrometer Performance characterization and use in the comparative analysis of histone H3 post-translational modifications. J Proteome Res 2004 3(3) 621-626. 

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

In its most commonly encountered form, the ion trap mass spectrometer is a low-resolution instrument used in dedicated GC— MS systems. Ions introduced into an electrostatic ion trap mass spectrometer perform stable oscillations within a cavity bounded by two hemispherical electrodes and one ring electrode. Ramping the potentials applied to the electrodes causes the oscillations to become unstable and the ions are fiung out of the trap in mass (m/e) order. 

FIGURE 7 Tandem mass separator. Sample ions enter mass selector 1, where the parent ions are separated. The selected ions next enter the collision chamber, where they collide with gas molecules to form the daughter ions, which are finally separated in the mass selector 2 and expelled for detection. Either magnetic sector or quadrupole mass analyzers or both types mixed can make up a tandem mass spectrometer. A single ion trap can also function as a tandem mass spectrometer performing the same processes as described above in the same location but in consecutive steps. 

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