Patent ID: 8563777

Claim:
A composition comprising an isotopically enriched heavy quaternary amine compound for use as a labeling reagent in mass spectrometry according to the formula: wherein Y − is a suitable anion; wherein X is NH 2 or NH 3 ; wherein any number of carbons in the compound are 12 C or 13 C; wherein any number of nitrogens in the compound are 14 N or 15 N; wherein R 22 is selected from the group consisting of a bond; C 1 -C 30 linear or branched, saturated or unsaturated alkylene; aryl, aliphatic ring, oxygen-containing aliphatic ring, halogenated aryl, O, C 1 -C 12 linear or branched ether, C 1 to C 12 linear or branched polyether, C 1 -C 28 branched or linear ester, and, C 1 -C 28 branched or linear amide; wherein R 20 and R 21 are each independently selected from a group consisting of C 1 -C 4 branched or linear, saturated or unsaturated alkyl groups, wherein at least one of R 20 or R 21 contains at least one carbon that is 13 C or at least one hydrogen that is deuterium; and wherein the isotopically enriched heavy quaternary amine compound is present in an amount in excess of the natural isotopic abundance.