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
14.2%
Rate breakdown
9903.05.5510%Section 301 (forced labor) — additional 10% ad valorem on products of Mexico
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