Nitrosylsulfuric Acid (HNSO5) from China
Nitrosylsulfuric acid, also known as chamber acid or sulfonitric acid, is a chemically defined inorganic compound with the formula HNO2SO4 or [NO]+[HSO4]-. It falls under HTS 2808.00.00.20 as a sulfonitric acid, a mixed acid containing both nitric and sulfuric acid functionalities, classified in Chapter 28 for inorganic acids.
Duty Rate — China → United States
37.5%
Rate breakdown
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)
9903.05.3112.5%Section 301 (forced labor) — additional 12.5% ad valorem on products of China
Import Tips
• Classify strictly as sulfonitric acids per Chapter 28 notes; provide chemical analysis certificates confirming composition to avoid reclassification
• Comply with DOT hazardous material shipping requirements (UN 1791, corrosive liquid); include Safety Data Sheets (SDS) and proper labeling
• Verify importer security filing (ISF) for chemicals; common pitfall is incorrect storage class leading to inspection delays