THE OPERATION OF MASS SPECTROMETER

• The mass spectrometer has five basic operations:

           1) vapourization 2) ionization 3) acceleration 4) deflection and 5) Detection

• The diagram below shows the 5 main components in mass spectrometer

• The 5 stages are:

           Stage 1:          Vapourization

            The diagram above shows a vapourized sample is injected into the instrument. This allows the individual atoms of the element to be analysed.

             Stage 2:          Ionization

                   The diagram above shows the atoms are hit with high-energy electrons which knock out electrons, thus producing positively charged ions:

                                X(g)    +    e^-    →  X⁺(g)   +   2e^-

In practice, the instrument can be set up to produce only singly charged positive ions.

               Stage 3:          Acceleration

                     The diagram above shows the positive ions are attracted to negatively charged plates. They are accelerated by an electric field and passed through a hole in the plate.

             Stage 4:          Deflection

                         The diagram above shows the accelerated positive ions are deflected by magnetic field placed at right angles to their path. The amount of deflection is proportional to the charge/mass ratio. Ions with smaller mass are deflected more than heavier ions. Ions with higher charges are deflected more as they interact more effectively with the magnetic field.

                  Stage 5:          Detection

                      The diagram above shows positive ions of a particular mass/ charge ratio are detected and a signal sent to a recorder. The strength of the signal is a measure of the number of ions with that charge/mass ratio that are detected.International Baccalaureate animated chemistry courseware

**ALL THE PHOTO DIAGRAM ARE CAPTURED FROM INTERNATIONAL BACCALAUREATE ANIMATED CHEMISTRY COURSEWARE**