Before revision: The stable isotope composition of amino acids refers to the abundance of heavy and light isotopes of carbon (13C and 12C), nitrogen (15N and 14N) and other elements within these molecules.
After revision: non-radioactive,The stable isotope composition of amino acids refers to the abundance of heavy and light isotopes of carbon (13C and 12C), nitrogen (15N and 14N) and other elements within these molecules.