Nitrosylsulfuric Acid (HNSO5)
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.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If classified broadly as nitric acid without specific sulfonitric identification
Parent heading 2808 covers nitric acid generally, but subheading .20 specifies sulfonitric acids; customs may require proof of mixed acid nature.
If containing significant cyanogen derivatives or classified as complex nonmetal acids
Chapter Note 3 directs certain complex acids to 2811; applies if sulfonitric acid is interpreted as a nonmetal acid complex rather than simple sulfonitric.
If imported as a mixture with organic stabilizers or not chemically defined
Chapter Note 2 excludes organo-inorganic compounds and undefined mixtures from Chapter 28, directing them to mixtures heading 3824.
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Import Tips & Compliance
• 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
Related Products under HTS 2808.00.00.20
Fuming Sulfonitric Acid Mixture
A fuming sulfonitric acid solution combining concentrated nitric acid (HNO3) and sulfuric acid (H2SO4) in nitrosylsulfuric form, used in nitration processes. Classified under HTS 2808.00.00.20 as it meets the definition of sulfonitric acids per Chapter 28 notes for chemically defined inorganic acids.
Chamber Process Sulfonitric Acid
Sulfonitric acid produced via the chamber process for sulfuric acid manufacturing, existing primarily as nitrosylsulfuric acid. It is classified in HTS 2808.00.00.20 as a sulfonitric acid, distinct from pure nitric acid under the same heading.
Industrial Nitrosulfuric Acid Solution 98%
A 98% pure aqueous solution of nitrosylsulfuric acid used in organic synthesis and explosives manufacturing. Falls under HTS 2808.00.00.20 as a chemically defined sulfonitric acid per Chapter 28 definitions, excluding organo-inorganic mixtures.