Brief introduction to mass spectrometry

Mass spectrometry characterises substances by identifying and measuring the intensity of molecular fragment ions of different mass-to-charge ratio (m/z). 

The gas molecules entering the mass spectrometer from the thermobalance are first ionised in the ion source. The positive molecular ion and fragment ions formed are then separated according to their m/z value by a combination of magnetic and electrostatic fields. A mass spectrum is recorded by scanning the field strength so that ions of increasing m/z ratio arrive at the detector. 

In a TGA-MS system, the mass spectrometer is usually set to monitor individual m/z values that are characteristic of specific structural features. 

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These fragmentations serve to illustrate many of the major types. The driving force behind all of them is the formation of stable cations and radicals. Fragmentations of functional groups that have not been covered here are often similar to those described earlier. Although this has been only a very brief introduction to mass spectrometry, the power and utility of this technique should be apparent. 

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