Mass Spectrometer

Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of ions, producing a mass spectrum, a plot of ion abundance against that ratio, which scientists use to identify what elements or compounds a sample contains, work out molecular masses, and determine chemical structure. The instrument first ionizes a sample, turning its neutral molecules into charged particles, then passes the ions through a mass analyzer that separates them by mass-to-charge ratio using electric or magnetic fields, before a detector records how many ions of each kind arrive to build the spectrum. The groundwork was laid in 1886 when Eugen Goldstein observed positively charged rays in gas discharges, and Wilhelm Wien later built a device using crossed electric and magnetic fields to separate ions by charge-to-mass ratio; the modern mass spectrometer was established by Arthur Jeffrey Dempster and Francis William Aston in 1918 and 1919.