The mass spectrometry

• No other isotope or atom has a whole number as their mass number other than carbon 12
• Stage 1: Vacuum


  Whole apparatus is kept under vacuum condition to prevent the ions that are produced colliding with molecules in the air
• Stage 2: Ionisation (Electrospray and Electron impact)


  Electrospray - Sample dissolved in volatile solvent and forced through a fine hollow needle which is connected to the positive terminal of a high voltage supply, produces positively charged droplets, solvent evaporates and leaves ion behind
• Stage 2: Ionisation (Electrospray and Electron impact)


  Electron impact - Sample vaporised and high energy electrons are fired at the sample by an electron gun (hot wire filament with current running through it that emits a beam of high energy electrons). This usually knocks an electron off it forming a 1+ ion

  X(g) + e- ---> X+(g) + 2e-
• Stage 3: Acceleration


  Positive ions attracted to a negatively charged plate and accelerate towards it, lighter ions (less neutrons) means they'll get to the plate faster
• Stage 4: Ion drift


  Ions pass through a small hole in the negatively charged plate, forming a beam and travel along a tube (flight tube) to the detector
• Stage 5: Detection


  When ions of the same mass arrive at the same time, they create a current by picking up an electron and time of flight can be calculated.
• Stage 6: Data analysis


  Signal is transferred to a computer which generate a mass spectrometry
• Isotopes of Chlorine


  35Cl : 37Cl

  3 : 1