Meaning of precursor ions

[astroguille]

Hi!!!
I work with a MSD 5973.
The tune evaluation report shows high precursor ions. What does that mean?

[MIB_EO]

I don't know that specific instrument what type - Quad / trap / tof - is it?

However precursor ions usually means poor peak shape - a bump or other irregularity at the front of the peak. This is sometimes caused by a dirty front end often the extraction quad or hexapole. Follow your manual for how to remove the source and carefully clean these. Other causes can simply be poor tuning, particularly on quadrupole instruments.