How to Read Active Matter and Free Amine on an Amine Oxide COA
2026-11-10
How to Read Active Matter and Free Amine on an Amine Oxide COA
Two drums of amine oxide can have the same active content and different levels of residual free amine. For a formulation team, the first result helps determine how much surfactant to dose. For the receiving lab, the second result is a separate check against the agreed quality limit. Commercial product bulletins and published process examples report these values separately. pt.stepan.com
What the two COA entries measure
| COA entry | What it tells you |
|---|---|
| Amine oxide active matter | How much of the supplied material is the target amine oxide surfactant, on the stated reporting basis. |
| Residual free amine | How much unreacted tertiary amine remains in the supplied amine oxide, as measured by the stated method. |
C12–14 alkyldimethylamine is a tertiary amine intermediate. A published oxidation process uses a blend of C12 and C14 tertiary amines to make the downstream amine oxide. On the downstream product’s COA, residual free amine refers to feedstock that remains after oxidation. patents.google.com
How this affects batch acceptance
Suppose two incoming lots both report 32.1 wt% amine oxide active matter. Lot A reports 0.18 wt% free amine, while Lot B reports 0.42 wt%. If the agreed free amine maximum is 0.30 wt% and both labs use the same method and reporting basis, Lot A meets that limit and Lot B exceeds it. These figures are a hypothetical purchasing example.
When qualifying an amine oxide for a cleaning formulation, ask the supplier to state the active matter range and free amine maximum separately. Confirm the test method and reporting basis for each result. If the COA gives an equivalent weight for the free amine calculation, include that detail when comparing results across suppliers or labs. pt.stepan.com
If you manufacture amine oxide and are sourcing C12–14 alkyldimethylamine, share your incoming feedstock requirements with China Amines Co., Limited. Ask for the current grade specification and a representative COA for the tertiary amine intermediate.
Technical references
- US6054616A — Residual raw materials in tertiary amine oxides
- US9085515B2 — Continuous process to make amine oxide
- Stepan — Lauramine oxide product bulletin