Heading 330124 is restricted to oil derived from Mentha piperita specifically. Other mint species — including cornmint (Mentha arvensis) and spearmint (Mentha spicata) — fall under 330125. Because cornmint oil is sometimes sold commercially as a peppermint substitute, importers should require botanical source documentation to ensure correct classification and avoid misdescription.

Buyers in pharmaceutical and oral care markets typically specify minimum menthol content, menthone-to-menthol ratio, and optical rotation (to confirm natural L-menthol dominance). ISO 856 and the European Pharmacopoeia monograph are common reference standards. Importers should request a full GC/MS certificate of analysis and, for drug or dietary supplement use, confirm that the supplier's facility meets FDA current Good Manufacturing Practice requirements.