Patent ID: 8679773

Claim:
A kit comprising: a) a set of two or more isobaric and/or isomeric reagents for the labeling of analytes, wherein all reagents of the set comprise the formula: or a salt thereof, wherein; i) RG is a reactive group that is an active ester wherein the alcohol moiety of the active ester is: wherein X′ is O or S; ii) Z is O, S, NH or NR 1 ; iii) each j is the same or different and is selected from the group consisting of: H, R 1 , OR 1 , SR 1 , NHR 1 , N(R 1 ) 2 , fluorine, chlorine, bromine and iodine; iv) one of A 1 , A 2 , A 3 , A 4 and A 5 is W, wherein W is selected from the group consisting of: NH, N—R 2 , P—R 2 , O and S; and v) the remainders of A 1 , A 2 , A 3 , A 4 and A 5 that isn't W have the formula C(J) 2 , where J is as defined above; vi) each R 1 is the same or different and is an alkyl group comprising one to eight carbon atoms which may optionally contain a heteroatom or a substituted or unsubstituted aryl group wherein the carbon atoms of the alkyl and aryl groups independently comprise linked hydrogen and/or fluorine atoms; and R 2 is an amino alkyl, hydroxy alkyl, thio alkyl group or a cleavable linker that cleavably links the reagent to a solid support wherein the amino alkyl, hydroxy alkyl or thio alkyl group comprises one to eight carbon atoms, which may optionally contain a heteroatom or a substituted or unsubstituted aryl group, and wherein the carbon atoms of the alkyl and aryl groups independently comprise linked hydrogen, and/or fluorine atoms; and wherein each reagent of the set is optionally isotopically enriched by replacing one or more atoms of the reagent with a corresponding heavier atom isotope; and b) one or more other reagents, containers, enzymes, buffers or instructions.