Suppose you were only interested in compounds that have an m/z 77
signal in the mass spectrum. This is part of the power of collecting
the three dimensional GC/MS data. Instead of plotting the total
ion current vs. time, one can choose to plot a single mass (or small
range of masses) signal vs. time. This Extracted Ion Chromatogram
(EIC) allows the mass spectrometer to be used as a selective detector.
One can display data only for peaks of interest in cluttered TIC's.
Exercise: Display the m/z 77 EIC for the file EVALDEMO.D. How many
of the detected compounds in the TIC show this fragment?
Exercise: Simultaneously display the m/z 154 and 188 EIC's for EVALDEMO.D.
Compare these chromatograms to the TIC and the m/z 77 EIC.