9902.05.40 - Tetrakis(hydroxymethyl)phosphonium sulfate (CAS No. 55566-30-8) (provided for in subheading 2931.90.90)

This HTS category, 9902.05.40, specifically classifies Tetrakis(hydroxymethyl)phosphonium sulfate (THPS), identified by CAS No. 55566-30-8. This chemical compound is typically used as a biocide in industrial water treatment, as a flame retardant, and in textile finishing processes. Its unique chemical structure and specific applications differentiate it from other classifications.

As a provision within Chapter 99, this code signifies a temporary measure or a special classification arrangement. It is important to note that this THPS classification is for the purpose of specific trade agreement provisions or temporary legislation and is *provided for* in subheading 2931.90.90, which covers other organo-inorganic compounds. This means that while THPS has a primary classification under 2931.90.90, its importation under certain circumstances or trade agreements may be subject to the temporary rules and duties outlined in this Chapter 99 code.

Given that this is a leaf node, there are no further subcategories. Classification under 9902.05.40 is therefore definitive for THPS when imported under the conditions stipulated by the temporary legislation or trade agreement provisions associated with Section XXII. Importers should ensure they are aware of the specific trade conditions that necessitate the use of this special classification code, as it is distinct from the general chemical classification.