a) Explain the concept of tandem mass spectrometry.
The term tandem mass spectrometry, or briefly tandem MS, encompasses the numerous techniques where mass-selected ions are subjected to a second mass spectrometric analysis. Tandem mass spectrometry comprises the acquisition and study of the spectra of ionic products or precursors of m/z-selected ions, or of precursor ions of a selected neutral mass loss.
b) Tandem MS experiments can be performed on multiple stages. What terms and acronyms are normally used to describe them?
Writing MS/MS works well as long as only two stages are employed.
When higher order tandem mass spectrometry is performed an exponent is used to assign the number of MS stages, e.g., MS3 rather than MS/MS/MS.
c) Depending on the instrumental setup there are two variants of how the actual tandem MS experiment can be realized: tandem MS in space and tandem MS in time. Assign these to the list of mass analyzers below.
- magnetic sector: in space
- time-of-fligth: in space
- quadrupole ion trap: in time
- linear quadrupole: in space
- linear quadrupole ion trap: in time
- Fourier transform ion cyclotron resonance: in time
d) Try to express the criterion for your selection in c) in one sentence.
Beam instruments are operated in tandem-in-space mode as they require one analyzer per ion-selecting stage while all ion trapping devices are run as tandem-in-time devices because they can store mass-selected ions for the next stage