How to Read a Mandarin Oil COA, Line by Line
A certificate of analysis that lists density, refractive index and optical rotation is a quick consistency check on an oil, and it is a good place to start reading paperwork. We publish one for our mandarin oil, so it makes a handy worked example. Here is each line, what it tells you, and what to ask for when you need more.
Mandarin Essential Oil
Our own Mandarin Essential Oil, in sizes from 0.5 oz to bulk.
From $12.99
Shop Now →Start with the lot and the date
Our posted certificate describes batch MANLUCCRBRC003A and prints a best-by date of 11/14/2025, which has now passed, so use it as a model of the document's layout. A certificate covers one batch; for any bottle you are about to buy, ask for the document for the lot that will ship, in writing, with the lot code that will be on your container. Do not try to decode a batch code. The sheet does not explain ours, and letters in a code are not evidence of anything. Our label guide covers bottle wording.
The sheet, line by line
| Line | Our printed result | What it tells you |
|---|---|---|
| Botanical name, part, extraction | Citrus reticulata; peel; cold pressed | The issuer's declaration of what the oil is |
| Appearance | Green liquid | Colour class: EFSA describes green mandarin oil as green to green-brown and red as orange to red-amber |
| Smell | Unique aroma of mandarin | A sniff test pass |
| Relative density, 20 C | 0.852 | How heavy the oil is against water |
| Refractive index, 20 C | 1.471 | How strongly light bends in it |
| Optical rotation, 20 C | +69.80 degrees | How far it turns polarised light |
The certificate's conclusion says all tested parameters comply with pharmacopoeia standards for mandarin oil. It does not name a laboratory, test method or test date. The standard methods for the three constants do exist: Pl@ntUse lists ISO 279 for relative density, ISO 280 for refractive index and ISO 592 for optical rotation (Physical properties of essential oils (PROSEA)), and asking which method a lab used is a perfectly normal question.
Three numbers that do real work
The first use is conversion. A density of 0.852 means 1 ml weighs about 0.852 g, so an ounce (29.57 ml) is about 25.2 g and a pound (453.6 g) is about 532 ml. That is the arithmetic that lets you buy by the ounce and formulate by the gram, for the batch measured. Our bottle-size article puts it to work.
The second use is a consistency screen. If a later lot reads far from these numbers, something has changed. For context, EFSA's specification for expressed mandarin oil gives density 0.844 to 0.859, refractive index 1.470 to 1.480 and rotation +61.5 to +81.5 degrees (EFSA Panel, 2021), and our three values fall inside those ranges. The limit is that bulk properties can be matched by more than one mixture, so they show that an oil behaves like mandarin, not that it is nothing but mandarin.
Reading the rotation figure
Rotation grows with the length of liquid the light travels through, so +69.80 degrees means one thing in a long tube and something quite different in a short cell. When you read any certificate, ask which path length produced the figure and which monograph's limits apply. A rotation set against the wrong window can look wrong or look right by accident.
What a GC-MS report adds
Gas chromatography separates an oil into its compounds and mass spectrometry names them. In EFSA's work on ten batches, up to 88 constituents were detected and 47 identified, covering about 99.7% of the peak area. That is where limonene, gamma-terpinene and methyl N-methylanthranilate show up with their shares; our composition article shows what the studies found. Authenticity research goes further still: a 2025 study profiled the chiral and isotopic fingerprints of 63 authentic mandarin oils and saw seasonal and geographical trends (Cannizzaro et al., 2025). Two limits are worth knowing. A Tisserand Institute article explains that classical GC-MS cannot find pesticides, so a composition report and a residue screen are different documents (The Highs and Lows of GC-MS in Essential Oil Analysis), and GC-MS alone may not settle every question of adulteration.
Our certificate carries no GC-MS data, constituent percentages, origin, flash point, allergen data or residue data. If you need any of those, or a safety data sheet or IFRA statement for a product you will sell, ask us in writing through the contact page before you order, and ask for the answer in writing too.
Reading it like a shopper, not a chemist
You do not need a laboratory background to get value from a certificate. Start with the simple things: does the product name match what you ordered, does the botanical name match what you expect, and is there a lot code you can match to a bottle? Then look at the appearance and smell lines and ask whether they match what you see and smell when you open your own bottle. The sheet describes a green liquid with the aroma of mandarin, and it is a good habit to hold paper and bottle side by side every time.
Keep a folder, paper or digital, with one certificate per lot you receive. When a new bottle arrives you can lay the sheets next to each other and see at a glance whether anything has moved. Write the date the bottle arrived on the sheet too, so the folder tells its own story a year from now.
And if a line on any certificate puzzles you, do not nod and move on. Write the question down and send it. Sellers who like their product are usually happy to explain it.
What to put in the order email
- The certificate for the lot that will ship, with the lot code and its best-by date.
- The test method for each constant and the optical rotation path length.
- If you need composition, a GC report for that lot naming its method and listing the minor compounds, not limonene alone.
- If you are selling a finished product, an SDS and an IFRA statement naming the Amendment number; our IFRA article explains why.
Keep each reply with your batch records. For larger quantities, our bulk page covers sizes, samples and the wholesale form. A certificate is the start of a good conversation with a seller, and the more specific your questions, the more useful the answers.
Read the sheet with the bottle open beside you, and it stops being paperwork and starts being useful.
Mandarin Essential Oil
Mandarin Essential Oil from our own shop, in sizes from 0.5 oz to bulk.
From $12.99
Shop Now →Sources & Further Reading
- EFSA Panel on Additives and Products or Substances used in Animal Feed, 2021. Safety and efficacy of a feed additive consisting of expressed mandarin oil from the fruit peels of Citrus reticulata Blanco for use in all animal species (FEFANA asbl). EFSA J. PMC8190682
- Pl@ntUse. Physical properties of essential oils (PROSEA). plantuse.plantnet.org
- Cannizzaro et al., 2025. Comprehensive analysis of mandarin essential oils: Simultaneous qualitative, quantitative, chiral, and isotopic profiling via enantio-selective multidimensional gas chromatography coupled to isotopic ratio mass spectrometry. University of Messina record
- Tisserand Institute. The Highs and Lows of GC-MS in Essential Oil Analysis. tisserandinstitute.org
