Patent Document ID: 20140093968
Application ID: 14000856
Patent Flag: 0

Claim One:
1. An isobaric labeling reagent set for use in quantitative measurement of peptides by mass spectrometry, comprising: a plurality of isobaric labeling reagents each comprising a reporter group, a mass normalizing group, a peptide-reactive group, and a cleavable linker attaching the reporter group to the mass normalizing group, each one of the plurality of isobaric labeling reagents having the same nominal mass; each one of the isobaric labeling reagents having a reporter group with a mass different from the masses of the reporter groups of each of the other isobaric labeling reagents, each reporter group having the same elemental composition; wherein a first collection of at least two of the isobaric labeling reagents have reporter groups of the same nominal mass but different isotopic substitutions.