Mass spectrometers are used widely in a wide variety of research and application areas. Advantages of the method are the high selectivity, short measuring times, good sensitivity, wide measuring dynamics and multi-component capability. The measuring principle is based on the ionization of atoms or molecules of the analyte, which are supplied to the system in gaseous form. The ions are separated and detected on the basis of their mass-to-charge ratio, whereby both a qualitative and quantitative statement can be made about the composition of the substance mixture investigated. The mass spectrometer of CEST is specialized in masses up to 100 amu.