... Quality√ First domestic L-Theanine manufacturer through USP auditAbout Us:Zhejiang Tianrui Chemical CO., Ltd., situated in south industrial ... D, production, sales and technical services of L-Theanine, L-Pyroglutamic acid, L-Glutamic acid etc. Our plant is designed, ... in technology. Through cooperation with domestic and foreign higher education institutes, and institutes of biology, we always ...