1-Naphthylamine-4,8-disulfonic Acid (Casella's Acid) from Mexico
Casella's acid features dual sulfonic groups on the 1-naphthylamine backbone, used in direct dyes. While not explicitly named, its structural similarity to listed 2921.45.25.00 compounds and retention of primary amine function justifies inclusion. Chapter 29's last-in-order rule prioritizes amine over sulfonated classifications.
Duty Rate — Mexico → United States
10%
Rate breakdown
9903.05.5510%Section 301 (forced labor) — additional 10% ad valorem on products of Mexico
Import Tips
• Document sulfonic group count and positions via MS/NMR for classification support
• Use low-temperature storage (<25°C) and declare stability data
• Separate from mono-sulfonic isomers to avoid mixture designation confusion