Start with the commercial product
Collect the common name, trade name, grade, purity and intended application. A broad label such as polyethylene or surfactants can include very different products.
Use HS and descriptions together
HS codes define tariff scopes. Declared descriptions help identify relevant records within that scope. Check the HS version and any national code extensions before combining series.
Use CAS as supporting evidence
A CAS identifier can help connect names, but it is not guaranteed to be present in customs data. A shared identifier does not establish that two grades or formulations are commercially interchangeable.
State the limits of the match
Keep the original description visible. Distinguish source fields from inferred labels, and leave uncertain records marked for review.