(-)-?-Amino-p-hydroxyhydrocinnamic Acid-13C9; Therigon-13C9; p-Tyrosine-13C9; (2S)-2-Amino-3-(4-hydroxyphenyl)propanoic Acid-13C9; (S)-2-Amino-3-(4-hydroxyphenyl)propanoic Acid-13C9; (S)-Tyrosine-13C9; (S)-?-Amino-4-hydroxybenzenepropanoic Acid-13C9; L-(-)-Tyrosine-13C9; Levodopa EP Impurity B-13C9
