Submitting samples for mass spectrometry

Agilent 5975C Triple Axis GCMS (GC MS, electron/chemical ionisation)

To submit a sample firstly complete a request form: Mass Spectrometry request form (Word).

There are 2 sample login computers in the MS room. On your first visit you will need to enter your details on the database via the new user button. Subsequently, select new entry and fill in your name, sample details, required ionisation technique and solvent. The software will generate a log number to be written on the form and sample, and will tell you where to leave your sample. Put the form in the appropriate tray. Samples must be submitted in the correct vial for each technique. If you have any queries, any member of the mass spec staff will help.

Results with the unused samples can be picked up from the out boxes opposite the login desk.

What to expect from the results:

EI Expect to see a peak at the molecular mass and sensible fragments from the molecule.

CI With Ammonia has chemical ionisation gas expect to see a peek at the molecular mass plus ammonia (i.e. molecular mass +18). With Methane has the chemical ionisation gas expect to see M + H+, M+CH4+, M + C2H3+, M + C3H5+

ES & APCI In positive mode, it is common to see addition of a positive ion, routinely H+, Na+ or K+. Dimers and trimers are often seen, which can also pick up a positive ion. Besides this you can often see additions of solvent to any of these ions. In negative mode expect to see loss of H+ or addition of a negative ion such as Cl- or Br-.

MALDI Expect to see addition of H+, Na+ etc. and sometimes a dimer.

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