Mercaptosuccinic Acid from Mexico
Mercaptosuccinic acid (HSCH₂CH(COOH)CH₂COOH) is a di-carboxylic acid with thiol functionality, classified under HTS 2930.90.4950. Contains sulfur directly bonded to carbon; excluded from cyclic anhydrides per note 8. Used in heavy metal chelation and polymer modification.
Duty Rate — Mexico → United States
110%
Rate breakdown
9903.04.6095.8%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
• Provide molecular weight and functional group analysis confirming non-cyclic structure
• Certify heavy metals <10ppm for chelation grade material
• Document acid dissociation constants to validate di-carboxylic acid status