2830 - Sulfides; polysulfides, whether or not chemically defined:

This HTS category encompasses a range of inorganic chemical compounds classified as sulfides and polysulfides. These substances are characterized by the presence of one or more sulfur atoms bonded to another element, typically a metal or metalloid. The key defining feature is the sulfur-to-element bond, differentiating them from elemental sulfur or other sulfur compounds where sulfur is in a different oxidation state or bonding configuration. This category includes both chemically defined compounds with established formulas and mixtures of sulfides and polysulfides.

When classifying within Chapter 28, it is crucial to distinguish these sulfides and polysulfides from other inorganic chemical products. Unlike elements (Chapter 2801-2805) or inorganic acids and bases (various other chapters), these compounds specifically involve the sulfur-sulfur or sulfur-element linkage characteristic of sulfides and polysulfides. Furthermore, they are distinct from organic sulfur compounds, which are classified under Chapter 29. The scope of this category is solely limited to inorganic sulfur compounds of this specific chemical nature.

Within the broader classification of sulfides and polysulfides (2830), further subdivisions exist to specify particular compounds or groups of compounds. For instance, subheadings may differentiate between specific metallic sulfides, such as sodium sulfides, and more general categories for "other" sulfides and polysulfides. These subdivisions facilitate more precise classification based on the specific chemical composition and intended application, aiding in accurate tariff assessment and trade statistics.