L-Tryptophan, Feed Additive, Amino Acid, Feed Grade/Amino Acid, Appearance:White crystals or pale yellow crystalline powder L-Tryptophan/Feed Grade/Amino Acid,CAS NO: 73-22-3,Certificate ... .5%0.14%Residue on ignition ≤0.5%0.10% L-Tryptophan, Feed Additive, Amino Acid