Mass Spectrometry
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What happens in mass spectrometry?
Vaporised organic sample is ionised (loses e-) and accelerated through mass spectrometer M(g) —> M+(g) + e- M+ (g) is detected (molecular ion) Spectrometer measures mass/charge ratio (m/z)
Why do mass spectra have many peaks?
Due to fragmentation. The excess energy from the ionisation process can transfer into the molecular ion, splitting it. This produces a smaller + ion and a radical. The smaller (FRAGMENT ION) is detected
How can you identify the original molecular ion in a mass spectra?
It is the peak furthest to the right with the largest m/z value because it is not fragmented.
What is the M + 1 peak?
Carbon has C - 13 isotope of only 1% abundance so it is a very small peak to the right of M+ peak
What molecular ion has an m/z value of 15?
CH3+
What molecular ion has an m/z value of 17?
OH+ (from alcohols)
What molecular ion has an m/z value of 29?
C2H5+
What molecular ion has an m/z value of 43?
C3H7+
What molecular ion has an m/z value of 57?
C4H9+