base peak

in mass spectrometry
https://doi.org/10.1351/goldbook.B00608
The peak in a @M03749@ corresponding to the separated ion beam which has the greatest intensity. This term may be applied to the spectra of pure substances or mixtures.
Sources:
Orange Book, 2nd ed., p. 206 [Terms]
PAC, 1991, 63, 1541. (Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)) on page 1554 [Terms] [Paper]