1-Naphthylamine-4,8-disulfonic Acid (Casella's Acid) from China
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 — China → United States
37.5%
Rate breakdown
9903.05.3112.5%Except for products described in headings 9903.05.85–9903.05.92, articles the product of China, as provided for in U.S. note 52 to this subchapter
9903.88.0325%Except as provided in headings 9903.88.13, 9903.88.18, 9903.88.33, 9903.88.34, 9903.88.35, 9903.88.36, 9903.88.37, 9903.88.38, 9903.88.40, 9903.88.41, 9903.88.43, 9903.88.45, 9903.88.46, 9903.88.48, 9903.88.56, 9903.88.64, 9903.88.66, 9903.88.67, 9903.88.68, or 9903.88.69, articles the product of China, as provided for in U.S. note 20(e) to this subchapter and as provided for in the subheadings enumerated in U.S. note 20(f)
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