Diquat-d4 (dibromide)is the deuterium labeledDiquat (dibromide)(HY-122984)[1]. Diquat dibromide is a comprehensive herbicide commonly used in the cultivation of cotton, soybeans, and other crops to combat unwanted weeds. Diquat dibromide has an IC50 of 60 mg/L in the Allium root growth inhibition test[2].