In a mass spectrometer are individual molecules of the sample ionized in the gas phase. Thereafter, the resulting ions are accelerated in a very precisely controlled electric field. The ions are then separated according to their mass / charge- ratio (m / z) which is followed by the detection . In a mass spectrum shows the intensity of each m / z .
A completely different analysis technique , FT -MS ( Fourier Transform - Mass Spectrometry ) uses a magnetic field in which the ions are trapped . A radio pulse brings them into resonance. This results in a resonance signal, which is measured in the time . By a Fourier transform of the measured signal is directly produced a very mass spectrum . This technique can achieve a very high resolution and has a particularly high efficiency.