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 ... %98.57%Specific rotation-29.0°—-33.0°-31.04° Chloride≤0.03%0.004% Sulfate≤0.03%0.0005% Heavy ... .14%Residue on ignition ≤0.5%0.10% L-Tryptophan, Feed Additive, Amino Acid