(3R)-Tryptophan EP Impurity I (Mixture of Diastereomers);1H-Pyrido[3,4-b]indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-methyl-, (3R)-;1H-Pyrido[3,4-b]indole-3-carboxylicacid,2,3,4,9-tetrahydro-1-methyl-,(3R)-(9CI);C13H14N2O2 (3R)-2,3,4,9-Tetrahydro-1-methyl-1H-pyrido[3,4-b]indole-3-carboxylic acid