Electrospray

• Ionisation

  Sample is dissolved in a polar volatile solvent and is put through a hypodermic needle attached to a positive terminal with a high voltage

  As particles leave the needle they are ionised and gain a proton
• Acceleration

  Particles are accelerated through a electric field consisting of 2 negatively charged plates, and therefore increase the kinetic energy of the ions

  Ions will accelerate at different speeds depending on their mass to charge ratio lower mz = greater acceleration higher mz = lower acceleration
• Ion drift

  ions enter a region with no electric field, so they drift at different speeds depending on their mass to charge ratio
• Detection

  Ions with a lower mz ratio reach the detector in less time than those with a higher mz, as they reach the detector electrons from the negative plate flow to the positive ions and a current is induced

  Time taken to move down the spectrometer is used to determine the mass of isotope

  Size of current induced is used to measure the abundance of isotope
• Equation for electrospray ionisation:

  X+ H+ = XH+