DAS (4,4'-Diamino-2,2'-stilbenedisulfonic acid) Technical Grade from Canada
Technical grade DAS is a high-purity form of 4,4'-diamino-2,2'-stilbenedisulfonic acid used in optical brightener production. It falls under HTS 2921.59.2000 due to its precise chemical identity as a chemically defined aromatic polyamine per Chapter 29 note (a). Impurities are minimal and do not alter its classification.
Duty Rate — Canada → United States
16.5%
Rate breakdown
9903.05.2910%Section 301 (forced labor) — additional 10% ad valorem on products of Canada
Import Tips
• Request supplier specs showing >95% purity to distinguish from 'other' polyamines in 2921.59.8000
• Declare exact CAS number (128-71-2) on entry documents for customs verification
• Check for stabilizer additions; per Chapter notes, these don't change classification if for safety/transport