Under HTS Chapter 29, a chemically pure compound (meeting defined purity thresholds) is classified in its specific subheading, while a mixture of aromatics — such as mixed xylenes below the purity threshold for individual isomers — is typically classified under a separate heading for mixtures or under Chapter 27 as a petroleum product. This distinction can significantly affect the applicable duty rate and trade-remedy exposure, making supplier certificates of analysis critical.

Standard documentation includes a commercial invoice, bill of lading, packing list, and certificate of analysis confirming chemical identity and purity. For tank vessel shipments, a cargo manifest and safety data sheet (SDS) are also required. If the product is subject to EPA TSCA requirements, a TSCA certification (either positive or negative) must accompany the entry filing.