Thiodiglycol (293070) and 2-(N,N-dimethylamino)ethanethiol (293010) are CWC Schedule 2 chemicals, and 2-(N,N-diethylamino)ethanethiol (293060) is also scheduled. Importers of these substances must comply with Commerce Department CWC regulations, including end-use certification and, in some cases, advance notification to the Organisation for the Prohibition of Chemical Weapons (OPCW).

Both grades are classified under subheading 293040 regardless of purity or intended use, because the HS classification is based on chemical identity rather than application. However, pharmaceutical-grade methionine imported as an active ingredient may trigger FDA review, while feed-grade methionine is subject to USDA and FDA feed-additive regulations. The duty treatment is the same, but the admissibility pathway differs.