Selected ion monitoring (SIM) is the practice of monitoring and recording ion currents at one or more selected ion m/z values with time, rather than recording full mass spectra, as sample is introduced into the ion source. Because the detector is integrating signal for a longer time at the relevant ion, limits of detection can be lowered, albeit at a cost of susceptibility of the experiment to unexpected interferences. Use of the terms multiple ion detection, multiple ion (peak) monitoring, and mass fragmentography have also been used but are discouraged. The terms single ion monitoring or multiple ion monitoring are sometimes used.
The term "selected ion monitoring" was found in the following pages: