Fmoc-Arg(Pbf)-OH-13C6 is the 13C labeled Fmoc-Arg(Pbf)-OH[1]. Fmoc-Arg(Pbf)-OH is an arginine derivative containing amine protecting group Fmoc. Fmoc-Arg(Pbf)-OH is a building block for the introduction of Arg into SPPS (Solid-Phase Peptide Synthesis)[2].