MASS SPECTROMETRY EXPLAINED

Mass spectrometry is an analytical technique that is used to measure the mass-to-charge ratio of a sample. To measure it, a sample first has to be ionized into gaseous form. Then it can be inserted into the mass analyzer, which measures the mass-to-charge ratio. The results from the mass analyzer are presented as a mass spectrum which is a plot of intensity as a function of the mass-to-charge ratio.

Therefore the 3 main components of any mass spectrometer are:

1. Ionization source
2. Mass analyzer
3. Detector

The ionization source, as the name suggest is responsible for ionizing the sample. This is necessary because all mass analyzers utilize the interaction between an electric field and the ionized sample. Therefore the sample requires a charge in order for the mass analyzer to do this job. One can use one of several different techniques in order to ionize the sample. These are electron ionization, chemical ionization, electrospray ionization and matrix assisted laser desorption ionization. I either have covered or will soon cover every single one of these ionization techniques in more detail in other videos and I will link the playlist where you can find all of them by the end of this video! Once the sample has been ionized it gets passed along to the mass-analyzer.

Here again, there exist multiple different mass analyzers which we can choose between. These are quadrupole mass analyzer, time of flight mass analyzer, magnetic sector mass analyzer, electrostatic sector mass analyzer, quadrupole ion trap mass analyzer and ion cyclotron resonance mass analyzer. Again, I either have already covered or will cover all of these topics and the videos exist in the same playlist as the ionization techniques. How the mass-to-charge ratio gets measured varies widely depending on the mass analyzer in question!

Finally, the results are displayed in a so-called mass spectra graph, which I have also covered in a separate video available in the same playlist. The basic idea is that the components of the sample are displayed based on their size, in atomic units, and relative abundance. So if we look at the mass spectra graph displayed here, the bar furthest to the left displays the smallest component in the sample and the bar furthest to the right displays the largest. Then this bar here indicates which sub-component there is most of.