ABSTRACT
The chapter begins with a definition of a mass spectrometer. A mass spectrometer is an apparatus that quickly separates moving ions according to the value of their ratio mass/electric charge. Most often, these ions are positively monocharged but this is not obligatory. Then, the historical Aston's apparatus is described as an introduction to the configuration of such apparatuses and the principle of their functioning. A list of their different components is given. The double focusing mass analyzer is particularly investigated concerning its functioning. Then, an elementary description of a mass spectrum is given as is the case for a simple example of fragmentation. A comeback on analyzers with particularly general considerations of their characteristics is given. They are the ranges of worked ratios m/z, their transmission, their scan rate and their resolution.
