H Acid Coupling Component from Mexico
H Acid (1-amino-8-naphthol-3,6-disulfonic acid) serves as an azo coupling agent for substantive dyes on cotton. Though primarily phenolic, its role in azo dye synthesis links it to products in additional U.S. note 3 under HTS 2927.00.40.00. This chemically defined compound is essential for dye chemistry per chapter scope.
Duty Rate — Mexico → United States
110%
Rate breakdown
9903.04.6093.5%Except as provided in heading 9903.04.61, patented pharmaceutical articles as provided for in subdivisions (c) and (d) of U.S. note 40 to this subchapter
9903.05.5510%Except for products described in headings 9903.05.85–9903.05.92 and 9903.05.94, articles the product of Mexico, as provided for in U.S. note 52 to this subchapter
Import Tips
• Ensure documentation specifies use in diazo coupling to justify note 3 classification over general aromatics
• Test for heavy metal impurities; sulfonated compounds often require REACH-like compliance data
• Ship in stabilized aqueous solution only if per chapter note (d) for water-dissolved products