next up previous contents
Next: 7.3.1 Total Ion Chromatogram Up: 7. Overview of the Previous: 7.2 Methods   Contents

7.3 Some How-To's of Manipulating MS data

GC/MS data is a three dimensional matrix of information: scan number (related to the time since injection), mass and signal intensity.

As a run progresses, the spectrometer is typically scanned (for scan mode operation) over the mass range specified in the method. During each scan, the entire mass spectrum is collected and stored. In essence, the mass spectrum is collected as a function of time. Data can also be collected in the Selected Ion Monitoring (SIM) mode; in this mode, only some mass data are collected rather than the full spectrum.


John S. Riley, DSB Scientific Consulting