2918.13 - Salts and esters of tartaric acid:

This HTS category, 2918.13, specifically encompasses salts and esters derived from tartaric acid. Tartaric acid itself is a dicarboxylic acid commonly found in grapes and other fruits. Its salts and esters represent chemically modified forms of this acid, often utilized in various industrial applications, including food and beverage production, pharmaceuticals, and chemical synthesis.

It is crucial to distinguish this category from its sibling entries. While 2918.12.00.00 covers the pure tartaric acid, and 2918.14.00.00 covers citric acid, and 2918.15.00.00 deals with salts and esters of citric acid, category 2918.13 is exclusively focused on the tartaric acid derivatives. For instance, lactic acid derivatives are classified under 2918.11, and gluconic acid derivatives under 2918.16, highlighting the specific chemical parentage that defines each subdivision.

Within the salts and esters of tartaric acid, further distinctions are made at the subheading level to accommodate specific common derivatives. These include potassium antimony tartrate (tartar emetic), potassium bitartrate (cream of tartar), and potassium sodium tartrate (Rochelle salts), all of which have distinct properties and applications. A general "Other" subheading exists to capture any remaining salts and esters of tartaric acid not specifically itemized.