Organic analysis

HideShow resource information

Mass spectroscopy:

(more detail on other notes) 

The peak at the highest m/z on the mass spectrum is formed by the heaviest ion that passes through the mass spectrometer. This means that unless all the molecules of the original substance break up, this corresponds to the molecular ion and overall mass of the sample substance. 

The position of this molecular ion peak provides information about the molecular mass of a substance

Explaination for the peaks on the spectrum: 

- Many of these molecular ions will break up as some of the bonds between them are broken up when ionised. This fragementation therefore produces many smaller ion peaks which are smaller and can be used as a fingerprint to help deduce the structure of the compound. 

- The tallest peaks come from the most stable species. 


- Isotopes mean that many compounds will have more than one molecular ion peak. 

Important isotopes to know: 

  • Carbon:         99% C-12        and        1% C-13
  • Chlorine:        75% Cl-35       and        25% Cl-37
  • Bromine:        50% Br-79       and       50% Br-81


These isotopes produce smaller peaks which are comprised of the different isotopes of the compound and various combinations of these (as…


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Spectroscopy resources »