Patent ID: 7851647

Claim:
A labeled compound having the structure: wherein l=12 or 13, m=12 or 13 and n=12 or 13 with the proviso that l, m, and n do not simultaneously equal 12; wherein R is selected from the group consisting of alkyls and aryls; wherein Z 1 is selected from the group consisting of H and 2 H; wherein Z 2 is selected from the group consisting of H and 2 H; and wherein —X is selected from the group consisting of wherein R 1 is selected from the group consisting of alkyls and aryls; wherein k=12 or 13; wherein Z 3 is selected from the group consisting of H and 2 H; wherein Z 4 is selected from the group consisting of H and 2 H; and wherein M + is selected from the group consisting of Li + , Na + , K + .