Under TSCA Section 13, importers must certify at entry that a chemical substance or mixture either complies with TSCA or is not subject to it. For specialty preparations containing novel or unlisted chemical substances, a positive compliance certification requires that the substance appear on the TSCA Chemical Substance Inventory or that an applicable exemption applies — otherwise a Pre-Manufacture Notice (PMN) may be required before importation.

When a preparation's primary function is ambiguous across chapters, CBP's General Rules of Interpretation — particularly GRI 3(b) on essential character — guide the analysis. For complex mixtures, the dominant ingredient by weight, value, or functional role typically determines the chapter. A binding ruling request to CBP is the most reliable way to secure classification certainty for high-value or recurring specialty chemical shipments.