<P> Mass spectrometers are also widely used in space missions to measure the composition of plasmas . For example, the Cassini spacecraft carried the Cassini Plasma Spectrometer (CAPS), which measured the mass of ions in Saturn's magnetosphere . </P> <P> Mass spectrometers were used in hospitals for respiratory gas analysis beginning around 1975 through the end of the century . Some are probably still in use but none are currently being manufactured . </P> <P> Found mostly in the operating room, they were a part of a complex system, in which respired gas samples from patients undergoing anesthesia were drawn into the instrument through a valve mechanism designed to sequentially connect up to 32 rooms to the mass spectrometer . A computer directed all operations of the system . The data collected from the mass spectrometer was delivered to the individual rooms for the anesthesiologist to use . </P> <P> The uniqueness of this magnetic sector mass spectrometer may have been the fact that a plane of detectors, each purposely positioned to collect all of the ion species expected to be in the samples, allowed the instrument to simultaneously report all of the gases respired by the patient . Although the mass range was limited to slightly over 120 u, fragmentation of some of the heavier molecules negated the need for a higher detection limit . </P>

What is mass spectrometry and how does it work