By David Fowkes on Friday, 20 December 2019
Category: Chemistry A Level

Mass spectrometry

 Background

 how it works

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​A mass spectrometer "sorts" particles according to their mass. A mass spectrum gives the relative abundance of particles of different masses. With an element - the relative abundance of the isotopes is given .This data is then used to calculate the relative atomic mass of the element. 

When an organic molecule is analysed in a mass spectrometer the vaporisation and bombardment by high energy electrons process also fragments the molecule. 

​Ions are detected . Uncharged fragments will not be accelerated by the magnetic field and therefore get drawn out of the spectrometer by the vacuum pump.

This produces a fragmentation pattern which provides a "fingerprint" for the molecule but also other information which can help identify the molecule.

​Study the two infra red spectra on the left. One is propan- 1- ol, the other is propan 2 ol. Which is which?

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​Intro image