Mass Spectrometer	Spectrum analysis	Operation of a MS

simplified description of the operation of the mass spectrometer:

The principle function of a soft-ionisation Masspectrometer

1. The test gas is drawn in from the empty bottle.
2. The capillary sucks a tiny portion from the test gas and then reduces the pressure to high vacuum.
3. The gas is fed into the Octopole
4. Xenon gas is injected into the vacuum chamber and ionized (loaded electrically). Then the ionized Xenon gas is mixed with Test gas sample. Thus the molecules of the test sample are charged and can then be controlled by means of electrical fields within the vacuum chamber. The main point is that this soft ionization does not destroy the molecules.
5. The gas is conducted along a hollow space formed by 4 rods. These are controlled by means of an electrical rotating field . This rotating field only lets pass molecules whose mass corresponds to its frequency and tension . This function sorts the molecules by the mass .
6. At the end of this filter the molecules are counted by a Channeltron. By gradually changing the frequency and the tension of the rotating field, the concentration for every mass can be determined.
7. This information forms a mass spectrum. The proportional composition results in a specific spectre, a kind of finger-print representing the substance.
8. By comparing the spectrum measured to the spectra recorded in the libraries, it is possible to compute the closest correspondence. In case of a close correspondence, the product is identified. If the score is low, the substance is unknown and rejected. The residues of soft drinks are subject to various fermentation processes, therefore the library needs to as comprehensive as possible.