The core acceptance indicators for tea tree oil are measured Terpinen-4-ol ≥40% under ISO 4730:2017, 1,8-Cineole ≤15%, p-Cymene ≤2%, batch variation below ±2% (SD ≤±1.5%), with OOS investigation on any out-of-spec value and chiral R/S analysis required to prove natural origin.

The key specification of michelia leaf oil is Linalool content ≥70% as a hard gate (below is excluded before price comparison), with perfumery grades requiring (R)-Linalool ee ≥90%, methyl eugenol below IFRA limits, and batch consistency verified by batch-matched third-party GC-MS reports with Linalool variation ≤±2%.

The core specification of blue gum eucalyptus oil is 1,8-cineole content of 70–85% (FCC grade ≥70%, USP grade ≥85%). A supplier passes acceptance only when the batch stays stable in the mid-range of 75–82% with batch-to-batch deviation ≤1.5 percentage points, verified through batch-matched third-party GC-MS and a COA with 15+ test items.

The key specifications of white michelia oil are Linalool content ≥55% (premium ≥70%), free acid value ≤5.0 (limit ≤7.0) and ester value ≥25.0 (minimum ≥20.0). Linalool content is the first decision factor that determines aroma strength, ingredient grade, price band and formula compatibility for US manufacturers.