Mass Spectrometry
Chemistry: IB Diploma Higher Level, topic 1.2.4
Mass Spectrometry
Mass spectrometry (MS) is widely used in chemistry, forensics, medicine, environmental science, and many other fields to analyze and help identify the substances in a sample of material.
Mass spectrometry - process
- In a typical mass spectrometer, the sample is vaporized and exposed to a high-energy electron beam.
- This beam causes the sample’s atoms (or molecules) to become electrically charged, typically by losing one or more electrons.
- These cations then pass through a (variable) electric or magnetic field that deflects each cation’s path to an extent that depends on both its mass and charge.
Mass spectrometry
Mass spectrum
- The ions are detected, and a plot of the relative number of ions generated versus their mass-to-charge ratios (a mass spectrum) is made.
- The height of each vertical feature or peak in a mass spectrum is proportional to the fraction of cations with the specified mass-to-charge ratio.
- Since its initial use during the development of modern atomic theory, MS has evolved to become a powerful tool for chemical analysis in a wide range of applications.
Analysis of mass spectra
- The occurrence and natural abundances of isotopes can be experimentally determined using a mass spectrometer.
- We will go through this in more detail in the next section.
A mass spectrum
Test yourself on Mass Spectrometry
The occurrence and natural abundances of what can be experimentally determined using a mass spectrometer?