In a preferred embodiment, R is an acyl group wherein R1 is methyl such that the labeled compounds are methanol , acetates wherein said 13C {HEAD ~ atom} is directly bonded to {TAIL ~ exactly one or two deuterium atoms} 
is directly bonded to
In a preferred embodiment , R is an acyl group wherein R1 is methyl such that the labeled compounds are methanol , acetates wherein said 13C { HEAD ~ atom } is directly bonded to { TAIL ~ exactly one or two deuterium atoms }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL