A certificate of analysis (CoA) is the document that answers one question: did this specific batch actually meet the specification it was made against? Without a CoA, a specification is a target on paper; with one, you have evidence for a particular lot.
This guide explains what a CoA typically shows, the test items most commonly included for a supplement, the difference between in-house and third-party testing, and how a CoA is linked to the batch it describes.
💬 Planning your first production run and want to know what test results you will receive? See Japan-made supplement OEM for how documents move alongside production.
What a certificate of analysis shows
A CoA lists the tests run on a specific batch, the result of each, and the specification’s pass/fail limit for comparison, so the batch’s compliance can be read at a glance.
| Field | What it records |
|---|---|
| Product name and specification reference | Which product and which version of the specification the batch was tested against |
| Batch or lot number | The specific production run the results belong to |
| Manufacturing and expiry (or best-before) date | When the batch was made and its shelf-life end point |
| Test item | What was measured (assay, microbial count, heavy metal, etc.) |
| Specification limit | The pass/fail threshold from the specification |
| Result | The measured value for that batch |
| Testing method | The analytical method used, so results are comparable to future batches |
| Issuing laboratory and signature/date | Who performed or verified the testing, and when |
Typical test items for a supplement
Assay confirms the labelled ingredient amount is actually present; microbial and heavy-metal tests confirm the batch is safe; residual pesticide testing applies mainly to plant-derived ingredients.
| Test category | What it checks | When it typically applies |
|---|---|---|
| Assay (content/potency) | The measured amount of the active ingredient(s) against the amount declared on the specification and label | Every batch, for every active ingredient with a validated test method |
| Microbiological | Total viable count, coliforms, and for higher-risk products E. coli, Salmonella, yeasts and moulds; for products containing live bacteria, the viable count of the named strain(s) | Every batch, scope set by the specification and the dosage form’s risk profile |
| Heavy metals | Commonly lead, arsenic, cadmium and mercury, each against a specification limit | Every batch or on a sampling schedule, depending on the specification |
| Residual pesticides | Screened where the ingredient is a plant extract or botanical material that could carry agricultural residues | Plant-derived ingredients, particularly whole-herb or extract materials |
| Physical checks | Weight, disintegration or dissolution time (for tablets and capsules), appearance | Every batch |
Which items are actually tested, and how often, is set by the specification — a CoA can only report against limits the specification named in the first place, which is why the specification has to be finalised before testing has anything concrete to test against.
💬 Want to know which tests your target market typically expects to see on a CoA? Tell us the market and we will explain what is usually asked for. Start the conversation.
In-house testing versus third-party testing
In-house testing is faster and usually included in the production cost; third-party testing by an accredited laboratory adds independence that some markets and buyers specifically require.
| In-house testing | Third-party testing | |
|---|---|---|
| Who performs it | The factory’s own quality control laboratory | An external, often ISO/IEC 17025-accredited, laboratory |
| Typical speed | Faster, integrated into the production schedule | Slower, adds shipping and queue time for samples |
| Independence | Tested by the same organisation that made the product | Independent of the manufacturer |
| When it is asked for | Routine batch release | Buyer due diligence, some import registrations, disputed results, and tests the factory’s own lab is not equipped or accredited for |
A laboratory accredited to ISO/IEC 17025 has demonstrated its technical competence to produce accurate testing data under a recognised international standard, which is why some importers or registration routes specifically ask for third-party results from an accredited laboratory rather than accepting a factory’s in-house report alone. Asking early which kind of testing your market or your own buyers expect avoids a late request for a retest that the finished batch’s remaining samples may not support.
How a CoA is linked to its batch
A CoA is only meaningful when its batch number, product name and specification reference can be matched to the actual product in hand — mismatched documentation is a common cause of import delay.
The batch or lot number on the CoA should match the number printed on the product’s packaging or shipping documents, and the specification reference should match the version of the specification current at the time the batch was made. Keeping a record of which specification version was in force for each production run matters if a formula changes over time — an old CoA tested against a superseded specification is not evidence for a later batch made to an updated one.
Before you ask for a quotation
Decide the CoA scope you need before production, since it affects both testing cost and the schedule.
- Which test items your target market’s import or registration process expects to see
- Whether third-party testing is required, or in-house testing is acceptable
- Whether you need a CoA for every batch or can work to a sampling schedule
- The specification the CoA should be tested against, finalised in advance
- Who should receive the CoA, and in what format, for your own records
💬 Ready to plan the testing scope for your first production run? Tell us your target market and we will explain what is typically expected there.
Frequently asked questions
1. Is a certificate of analysis the same as a certificate of conformity?
Not quite. A CoA reports actual measured results for a specific batch. A certificate of conformity typically states that a batch meets a specification without necessarily listing every individual result — some buyers accept either, others specifically require a full CoA with individual results.
2. Does every ingredient in a formula get tested individually?
Usually the active ingredients are tested individually for assay, while the finished product is tested as a whole for microbiological and heavy-metal limits, since those risks apply to the product as consumed rather than to each raw material separately. The exact scope is set by the specification.
3. Can I request a specific testing method?
You can ask, and a factory will tell you whether it can perform that method in-house or needs to send the sample to a third-party laboratory. Some markets specify a required method for certain tests, which is worth checking before production.
4. How long is a certificate of analysis valid for?
A CoA describes one specific batch at the time it was tested; it does not expire in the way a licence does, but its relevance is tied to that batch’s own shelf life and to the specification version it was tested against.
5. Who keeps the certificate of analysis on file?
Both the factory and the brand typically keep a copy, and some import markets require the importer to retain batch records, including the CoA, for a set period as part of their own food-safety obligations. Check your own market’s requirement rather than assuming the factory’s retention period covers it.
Sources: ANAB, “Testing Laboratory Accreditation | ISO/IEC 17025” (anab.ansi.org/accreditation/iso-iec-17025-testing-laboratory/); International Organization for Standardization, “ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories” (iso.org/standard/66912.html); Japan Health and Nutrition Food Association, description of its certification testing safety/hygiene indicators including residual pesticides, heavy metals and microbial counts (jhnfa.org/health7.html); Consumer Affairs Agency and Ministry of Health, Labour and Welfare, food-category standards under the Food Sanitation Act (see the specification sheet guide’s sources for detail). Checked on 25 September 2026.