2852.10 - Chemically defined:

This HTS category, 2852.10, encompasses chemically defined inorganic or organic compounds of mercury. It specifically includes mercury compounds where the chemical structure and purity are precisely known. This excludes mercury amalgams, which are alloys of mercury with other metals, and non-chemically defined mercury substances. The focus here is on pure, synthesized, or purified mercury compounds rather than mixtures or forms where the mercury is a constituent part of a more complex, uncharacterized substance.

The distinction between 2852.10 and its sibling category, 2852.90 ("Other"), lies in the chemical definition. While 2852.90 covers all other inorganic or organic compounds of mercury not specifically defined chemically within this chapter, 2852.10 is reserved for those where the chemical identity is established. This ensures that precisely characterized mercury compounds are classified under this more specific heading.

Within 2852.10, further subcategories exist to delineate specific types of chemically defined mercury compounds. Subcategory 2852.10.10.00 specifically lists highly regulated compounds such as mercuric oxide, mercuric cyanide, mercuric oxycyanide, and mercuric potassium cyanide, often due to their toxicity and particular industrial or analytical applications. The residual subcategory, 2852.10.90.00, captures all other chemically defined mercury compounds that do not fall under the specific list, providing a comprehensive classification for these substances.