9902.05.21 - Thioglycolic acid (Sulfanylacetic acid) (CAS No. 68-11-1) (provided for in subheading 2930.90.49)

This HTS category, 9902.05.21, pertains to Thioglycolic acid, also known as Sulfanylacetic acid (CAS No. 68-11-1). This specific classification is designated under Chapter 99, which covers temporary legislation and modifications. Its presence here indicates that while the commodity itself may be classified under a more permanent heading, such as subheading 2930.90.49 for organic compounds containing sulfur, it is subject to specific temporary provisions. These provisions are typically implemented due to trade agreements or for purposes outlined in Section 22 of the Agricultural Adjustment Act.

Distinguishing this classification from its siblings within Chapter 99 is crucial. Chapter 99 is a broad category encompassing various temporary measures and restrictions. Therefore, 9902.05.21 specifically isolates Thioglycolic acid to address unique import circumstances. Unlike sibling categories within Chapter 99 that might cover other goods subject to temporary duties, quotas, or prohibitions, this entry is precisely focused on Thioglycolic acid. Its existence here signifies a distinct regulatory treatment applied to this particular chemical compound beyond its standard classification.

As this is a leaf node, there are no subcategories to introduce. The classification of Thioglycolic acid under 9902.05.21 is therefore specific and final for the purpose of temporary legislation. Importers and customs professionals should refer to the accompanying notes and regulations for Chapter 99 and the specific temporary proclamations associated with this HTS code to understand the full scope of its treatment, including any quantitative limitations, special duties, or reporting requirements that supersede its permanent tariff classification.