Mercaptosuccinic Acid from Mexico
Mercaptosuccinic acid (thiomalic acid) contains both mercapto and dicarboxylic acid functions in a single molecule. Falls under HTS 2930.90.4920 as 'other mercaptocarboxylic acids' since organo-sulfur takes precedence over oxygen functions per Chapter 29 classification rules. Used in heavy metal detoxification.
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 quantitative analysis showing free -SH and -COOH groups for dual-function classification
• Classify as UN 3265 Corrosive solid, pH <2 requires specific packaging
• Document research/pharma end-use to avoid 2917 polycarboxylic acid misclassification