total-ion current

The total-ion current (TIC) trace is the sum of the relative abundances of all the ions in each mass spectrum plotted against the time (or number of scans) in a data collection sequence. For example, the total-ion current trace in a GC/MS run is analogous to the output of a single-channel gas chromatography detector. The trace allows eluted peaks to be identified by an increase in the total-ion current over background. The scans corresponding to the eluted peak are averaged together to create the mass spectrum of the sample corresponding to  that peak.