Question

Mass spectrometry

You examine the MS data from a GC-MS analysis. You notice there is quite a lot of fragmentation but are ansure if the molecular ion is visible.Explain,in detail,why this might be the case and what you could do to ensure you can work out the molecular mass of the analyte?

Answer 1

Answer – We know the energy of the ionising electrons in the organic molecule is so great compared with bond energy and that result the molecules fragmentation gets possible. As the bond strong there is need more energy. There is formed radical cation when the organic molecules formed a positive ion, since there is only one electrons gets removed from the pair of the electrons.

These formed radical cation are gets further fragmented in presence of more energy like 70 eV and there are more ions formed than expected and due to that we notice there is quite a lot of fragmentation but are unsure if the molecular ion is visible. There are also mass spectra depends on the applied voltage and magnetic field. If it gets vary the new will gets the very disturbed spectra and we can’t identified or compare with standard one.

If we need the correct and unique spectra then we need to all the operating condition like energy of the ionization electron must be quoted. We need to always ionize the molecule using the less energy, since there is formed only molecule positive ion which is predominant and we can easily identified in the spectra.