2844.43.00.21 - Americium-241, californium-252, cesium-137, gadolinium-153, idium-192, promethium-147, radium-226, selenium-75, or ytterbium-169

This HTS category, 2844.43.00.21, specifically enumerates and classifies certain individual radioactive isotopes, including americium-241, californium-252, cesium-137, gadolinium-153, iridium-192, promethium-147, radium-226, selenium-75, and ytterbium-169. These are considered "other elements, isotopes and compounds" within the broader scope of radioactive materials. The classification focuses on these particular named isotopes in their elemental, isotopic, or compound forms, as well as alloys, dispersions, ceramic products, and mixtures that *contain* these specific listed isotopes.

This sub-heading is distinct from its sibling, 2844.43.00.28, which covers "Other" radioactive elements, isotopes, compounds, and mixtures not explicitly listed in 2844.43.00.21. Therefore, if a radioactive material contains one of the listed isotopes, it falls under this specific heading. If it contains other radioactive elements, isotopes, or compounds not mentioned here, it would be classified under the "Other" sibling.

As this is a leaf node, there are no further subcategories under 2844.43.00.21. Classification at this level is determined by the presence of the specifically named radioactive isotopes. The primary criterion is the identity of the radioactive element or isotope within the product.