H Acid Free Acid (4-Amino-5-hydroxy-2,7-naphthalenedisulfonic acid) from Japan
The free acid form of H acid is specifically enumerated in HTS 2922.21.1000 alongside its salts. Less common than salt forms but used where specific pH control needed in dye coupling. Highly water-soluble despite free sulfonic groups.
Duty Rate — Japan → United States
12.5%
Rate breakdown
9903.05.4912.5%Except for products described in headings 9903.05.85–9903.05.92, articles the product of Japan, with an ad valorem (or ad valorem equivalent) rate of duty under column 1 less than 12.5 percent, as provided for in U.S. note 52 to this subchapter
Import Tips
• Neutralization equivalence point titration confirms free acid content
• Stronger corrosivity requires UN 3265 class 8 designation
• Specialized ventilation for dust exposure during unloading