precursor ion scan

precursor ion scan

In a multistage/mass spectrometry (MS/MS) experiment, mass-selected precursor ions are induced to dissociate into product ions, which are then mass analysed by a second analyser.
The precursor ion scan is one of three common scans in the single-step MS/MS experiment, in which a second mass analyser is set at the mass of the selected product ion; the first mass analyser is scanned from that mass upwards, resulting in a mass spectrum that contains signals for all the precursor ions that dissociate to the selected product ion.