Paraxanthine Reference Standard
Paraxanthine is a caffeine metabolite with a xanthine (pyrimidine-containing) structure, supplied as analytical reference material. Falls under HTS 2933.59.70.00 for aromatic pyrimidines listed in additional U.S. note 3. Used in lab research and pharma development.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If not specifically in additional U.S. note 3
General other heterocyclic compounds in 2933.59.91 cover non-listed items.
If containing isotopic labels like radioactive isotopes
Isotope-modified compounds classify under Chapter 28 isotopes.
If sold as prepared lab chemical mixture
Composite lab chemicals fall outside pure Chapter 29 compounds.
Not sure which classification is right?
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Import Tips & Compliance
• Include stability data and intended research use declaration to avoid pharma drug scrutiny
• Use small package sizes (<1kg) typical for standards to prevent bulk chemical treatment
• Cross-check with FDA for any import alerts on xanthine metabolites
Related Products under HTS 2933.59.70.00
Aminophylline USP
Aminophylline is a heterocyclic compound containing a xanthine (purine) structure with pyrimidine rings, used as a bronchodilator for asthma treatment. It falls under HTS 2933.59.70.00 as an aromatic pyrimidine derivative listed in additional U.S. note 3 to section VI for specific organic chemicals. This classification applies to its pure chemical form for pharmaceutical use.
Theobromine Powder
Theobromine is a methylxanthine alkaloid with fused pyrimidine rings in its purine structure, used in pharmaceuticals and as a chemical intermediate. Classified under HTS 2933.59.70.00 due to its aromatic nature and inclusion in additional U.S. note 3 to section VI. It qualifies as a separate chemically defined heterocyclic compound.
Caffeine Anhydrous USP
Caffeine anhydrous is a purine alkaloid featuring pyrimidine rings, used in pharmaceuticals, energy products, and as a chemical standard. It is covered by HTS 2933.59.70.00 as an aromatic heterocyclic compound described in additional U.S. note 3 to section VI. The classification reflects its chemically defined structure.
Theophylline Monohydrate
Theophylline monohydrate is a methylxanthine with pyrimidine rings, used in respiratory medications. Classified in HTS 2933.59.70.00 as an aromatic compound per additional U.S. note 3 to section VI. The hydrate form remains a separate chemically defined organic compound.
Dyphylline USP Powder
Dyphylline is a xanthine derivative with pyrimidine structure, used as a theophylline alternative in bronchodilators. HTS 2933.59.70.00 applies to this aromatic heterocyclic compound listed in U.S. note 3. It is imported as high-purity USP grade.
Proxyphylline Pharmaceutical Grade
Proxyphylline, a hydroxyethyltheophylline with pyrimidine rings, serves as a mild bronchodilator. Covered under HTS 2933.59.70.00 for its aromatic pyrimidine structure in additional U.S. note 3. Supplied for API manufacturing.