Key points
- A certificate of analysis (COA) is a document issued by a laboratory that reports the tests run on a sample from one batch of a product: what was tested, the method used, the limit that applied and the result found.
- A certificate describes only the batch named on it. The batch or lot number should match the one printed on the pack in your hand.
- Check who ran the tests. An accredited laboratory is accredited for specific tests, and those tests are listed on its schedule of accreditation.
- A certificate reports measurements. It does not tell you what a product will do for the person using it.
What is a certificate of analysis? A certificate of analysis (COA) is a laboratory report on a sample from one batch of a product. It lists the tests that were run, the methods used, the limits applied and the results found. Some brands share one on request. This general guide explains the sections most certificates contain, how to match one to a pack, what accreditation means and what the document cannot show.
What a certificate of analysis is
A certificate of analysis, usually shortened to COA, is a report issued after a sample from a production batch has been tested. It lists the tests that were run, how they were run, what result was expected and what result was found.
Certificates are used in many industries, from chemicals to foods. Layouts vary between laboratories, but the information usually falls into the same few groups.
The sections you will usually see
Batch number, dates and product name
The top of a certificate identifies what was tested: the product name or a sample description, a batch or lot number, and the company that asked for the test. There are usually several dates, such as when the sample arrived, when it was analyzed and when the report was issued. You should also find the laboratory's name and address, a unique report number and the name of the person who authorized the report.
Tests, methods, limits and results
The body of the certificate is normally a table. Each row is one test, sometimes called a parameter: the amount of a named substance, the identity of an ingredient, a count of microorganisms or a search for specific contaminants.
Next to each test you will usually see a method (a published standard or the laboratory's own method code), a limit or specification (the range or maximum the result is judged against) and the result, with its units.
Two phrases are worth knowing. "Not detected" means the amount was below the lowest level the method can detect, known as the limit of detection. It does not mean zero. A "limit of quantification" is the lowest level the method can put a reliable number on. A clear certificate shows both, so you can see how sensitive each test was.
Results can be given per gram, as a percentage by weight, per milliliter or per serving, so compare like with like. The difference between an amount per serving and an amount per pack is covered in our guide What Does NRV Mean on a Supplement Label?
| Section | What to check |
|---|---|
| Product name or sample description | It names the product you bought, not only a raw ingredient |
| Batch or lot number | It matches the number on your pack exactly |
| Dates | The dates are complete and in a sensible order |
| Test or parameter | The tests cover the questions you care about |
| Method | A method is named for every test |
| Limit or specification | You know who set the limit |
| Result and units | Units are stated and comparable |
| Limit of detection or quantification | It is shown wherever a result says "not detected" |
| Conclusion | It agrees with the results above it |
| Laboratory details and signatory | A name, address and report number you can check |
The table lists section names only. A real certificate contains values; this layout deliberately does not.
Matching a certificate to the pack in your hand
Start with the batch or lot number: find it on the pack, then on the certificate. They should match character for character. Then check the product name and pack size. A certificate for a different product or an earlier batch tells you about that product or batch, not yours.
Look closely at what was sampled. Some certificates come from an ingredient supplier and describe a raw material before it was turned into the finished product. That is a different document from a certificate for the finished product.
If the numbers do not match, ask for the certificate that covers your batch.
Who ran the tests: accreditation explained
Accreditation is an independent check that a laboratory is competent to carry out particular tests. For testing laboratories, the international standard is ISO/IEC 17025.
In the UK, the United Kingdom Accreditation Service (UKAS) accredits laboratories against that standard. UKAS explains that the specific activities an organization is accredited for are listed on its schedule of accreditation, and that schedules are published on the UKAS website. A current schedule on the site confirms that the accreditation is in force.
The key detail: accreditation covers named tests, not everything a laboratory does. Compare the tests on the certificate with the tests on the laboratory's schedule.
Laboratories outside the UK are accredited by other national bodies, and UKAS takes part in international agreements for mutual recognition with them. UKAS also notes that in many sectors accreditation is voluntary, so an unaccredited laboratory is not necessarily doing anything wrong; it simply has not had that independent check.
It is also fair to ask whether the laboratory is independent of the company selling the product. For more on this, read Third-party testing: what it proves and what it does not.
What a certificate cannot tell you
A certificate records measurements on one sample, which gives it clear limits:
- It covers one batch. It says nothing about earlier or later batches.
- It covers only the tests listed. A substance that was not tested for is not reported.
- It describes the sample at the time of testing, not what happened to the product afterward in transport or on a shelf.
- It cannot show that a method was suitable for this particular product. Laboratories demonstrate that through method validation, which the Eurachem guide on the subject describes as showing a method is fit for its intended purpose.
- It does not describe what a product does for the person who uses it. That is a separate question, and a laboratory report does not answer it. For how we write about NAD+ itself, see the science page.
If you have doubts about a certificate, the laboratory's name and report number let you ask the laboratory directly whether it issued it.
Questions to ask a brand
Ask any brand for a certificate of analysis, and use these questions to read what comes back:
- Can you share the certificate for the batch number printed on my pack?
- Is it for the finished product or for a raw ingredient?
- Which laboratory issued it, and is that laboratory independent of your company?
- Is the laboratory accredited, and are these specific tests on its schedule of accreditation?
- Which methods were used, and what are the limits of detection?
- Who set the limits the results are judged against?
- Which contaminants were tested for, and which were not?
These questions apply to us as much as to anyone. We have not published manufacturing or testing documents for this product yet.
Frequently asked questions
What does COA stand for?
COA stands for certificate of analysis. It is a laboratory report on a sample from one batch of a product, listing the tests run, the methods used, the limits applied and the results found.
Does a certificate of analysis mean a supplement has been approved?
No. A certificate of analysis is issued by a laboratory about a batch. It is not an approval from a regulator, and it does not show what a product will do for the person using it.
How can I check a laboratory's accreditation?
For UK laboratories, search the UKAS website by laboratory name and open its schedule of accreditation, then check that the tests on the certificate appear on it. Laboratories in other countries are accredited by their own national bodies.
Sources
- ISO: ISO/IEC 17025:2017 General requirements for the competence of testing and calibration laboratories
- UKAS: Laboratory Accreditation - ISO/IEC 17025
- UKAS: Frequently Asked Questions
- Eurachem: The Fitness for Purpose of Analytical Methods: A Laboratory Guide to Method Validation and Related Topics (third edition)
