**A patchouli oil certificate of analysis (COA) is the batch-specific lab record that proves what you are actually buying. Read it in order: confirm the identity block (Pogostemon cablin leaf, CAS 8014-09-3), then check patchouli alcohol percentage, specific gravity, refractive index, optical rotation, and acid value against the exact grade you ordered.**
A COA is not marketing. It is a snapshot of one drum lot, signed by a lab, tied to a batch number and a date. Two barrels of “premium Sumatra” can carry different numbers, so the document — not the label — is what you verify before wiring payment.
Below is how a perfumery or cosmetics buyer works through the page, line by line.
What does a patchouli oil COA actually tell you?
Every credible COA opens with an identity block. This is where you confirm the material is what the invoice claims before you even look at the analytical numbers.
Check these fields first:
- Botanical name: Pogostemon cablin (the leaf, steam-distilled).
- CAS numbers: 8014-09-3 (also seen as 84238-39-1). EU buyers routinely require the CAS on file for REACH-style documentation.
- FEMA number: 2838, relevant if the oil touches flavor or fragrance regulatory work.
- Batch/lot number and manufacture date, plus a retest or best-before date — published patchouli COAs have carried retest dates as far out as April 2027, which matters for long-term contracts.
- Appearance and odor: color runs light-yellowish-brown through reddish to dark red-brown by grade; odor should read woody-balsamic, sweet-herbaceous, earthy, and spicy.
If any identity field is blank or mismatched, stop and query it. Before you accept the analytical section, cross-check every figure against the supplier’s patchouli oil COA package and the grade you agreed on.
Which parameter matters most — and what is PA%?
Patchouli alcohol percentage (PA%, the compound patchoulol; locally you’ll hear kadar PA) is the single most important number on the sheet. It drives grade, price, and fixative strength in a fragrance base.
Indonesian oil typically runs 28-34% PA and is often described in the 30-40% range. Indonesian exporter grade families SKUs (2022-2025) show the pattern clearly: Sumatra molecularly-distilled lines like quote Min 32 PA, quotes Min 34 PA, while Sulawesi dark grades such as sit at Min 28 PA.
One honesty rule: PA% is only meaningful if it comes from a GC-MS run. A number typed onto a COA with no chromatogram behind it is a claim, not a measurement. Ask for the GC-MS trace and confirm the PA figure matches it.
How do you read specific gravity, refractive index, and optical rotation?
These three physical constants are the lab’s fingerprint check. They tell you the oil is genuine patchouli and hasn’t been cut or adulterated. You read them as pass/fail against reference bands rather than “higher is better.”
| Parameter | What it checks | Reference band commonly seen | Reading it |
|---|---|---|---|
| Specific gravity (20-25°C) | Density vs water | ~0.952-0.975 | Outside the band suggests dilution or a different oil |
| Refractive index (20°C) | How light bends through the oil | ~1.503-1.513 | Drifting low can flag solvent cutting |
| Optical rotation | Direction and angle light is twisted | Negative (levorotatory), typically the -40° to -66° region | A positive or near-zero value is a red flag for patchouli |
Treat the exact figures as batch claims: they are only trustworthy when they appear on the actual lab COA for your lot, not copied from a generic spec sheet. Patchouli is soluble in alcohol and fixed oils and insoluble in water — a solubility note is standard and worth confirming.
What does acid value reveal about storage stability?
Acid value measures the free acids in the oil, and it doubles as an ageing and stability signal. A low acid value points to a fresher, more stable oil that will hold up over a long contract.
Indonesian exporters’ figures illustrate the spread by origin:
| Origin family | Typical PA% | Typical acid value |
|---|---|---|
| Sumatra (e.g. 302) | 30-32 | 4-6 |
| Sulawesi dark (e.g. ) | ~30 | 8-10 |
| Sulawesi (example) | 28 | under 15 |
Industry sources cite an acid value under 8 as indicating excellent storage stability. Sumatra grades tend to run tighter at 4-6, which is part of why Sumatra and Aceh oils are prized in fine fragrance. If you’re locking in a 12-18 month supply, the acid value tells you how the oil will behave months after it lands.
What identity and traceability fields must match your order?
The last read is a reconciliation pass. Line up the COA against your purchase specification and your compliance file.
Work through this checklist:
- Grade family matches what you bought: Dark, Light, Iron-free (steam distillation plus de-ironization), or MD (molecularly distilled).
- Origin matches — Aceh, North Sumatra, West Sumatra, Sulawesi (Manado), or Java — because origin shifts the expected PA and acid figures.
- Supporting documents are attached or offered: GC-MS, TDS, SDS/MSDS, and a Certificate of Origin at minimum. Premium and certified lines may add Kosher, Halal, COSMOS, or FSSC 22000.
- Dates are current: manufacture date recent, retest/best-before date beyond your consumption window.
- Batch number on the COA equals the batch number on the drum and the shipping paperwork.
A COA that reconciles cleanly on all five points is what separates a verifiable bulk order from a hopeful one.
Frequently Asked Questions
What is a good PA% to read on a patchouli oil COA?
For Indonesian oil, a COA in the 28-34% range is normal, and premium fine-fragrance lots often show Min 32-34% PA. There is no universal “good” number — match the PA% to your formula. Molecularly distilled grades push higher; standard commercial oil sits lower. Always confirm the figure ties to a GC-MS result.
Does a low acid value on a patchouli COA mean better quality?
A low acid value signals better storage stability, not automatically better aroma. Industry sources treat an acid value under 8 as excellent, and Sumatra grades commonly quote 4-6 versus 8-10 for Sulawesi. For long contracts it’s a genuine advantage, but you still judge scent and PA% separately — acid value alone doesn’t grade the oil.
Can I trust the PA% if a COA has no GC-MS report attached?
Treat it cautiously. A PA percentage is only a verified measurement when a GC-MS chromatogram supports it; without one, the figure is an unbacked claim. Request the GC-MS trace for your specific batch and check that the reported patchouli alcohol value matches the peak. Reputable suppliers provide it on request.