2831.10 - Of sodium:

This HTS category, 2831.10, specifically covers dithionites and sulfoxylates that are of sodium. These are chemical compounds characterized by the presence of a sodium cation and a dithionite ([S₂O₄]²⁻) or sulfoxylate ([SO₂]²⁻) anion. Sodium dithionite, also known as sodium hydrosulfite, is a potent reducing agent widely used in industries such as textiles for vat dyeing and indigo reduction, paper manufacturing for bleaching, and in various chemical synthesis processes. Sodium sulfoxylates, while less common, also exhibit reducing properties and find applications in specialized chemical processes.

Distinguishing this category from its sibling, 2831.90.00.00 ("Other"), is crucial. Category 2831.10 is exclusively for sodium-based dithionites and sulfoxylates. The "Other" sibling category encompasses dithionites and sulfoxylates of metals other than sodium, or those that are not specifically identified as sodium compounds and do not fall under any other more specific heading. Therefore, if a dithionite or sulfoxylate contains sodium as the primary cation, it will be classified here.

Within category 2831.10, further subclassification is provided to distinguish specific forms. The subcategory 2831.10.10.00 pertains to "Sodium formaldehyde sulfoxylate," a specific compound formed from sodium dithionite and formaldehyde, which possesses distinct chemical properties and applications, often used as a reducing agent or in photographic developers. The remaining subcategory, 2831.10.50.00 ("Other"), captures all other sodium dithionites and sulfoxylates not specifically identified as sodium formaldehyde sulfoxylate, allowing for the accurate classification of various sodium-based reducing agents within this heading.