What Is a Certificate of Analysis (COA) and Why Is It Important?

What is a Certificate of Analysis? A COA is a document issued by a manufacturer or laboratory that reports the test results for one specific lot of a product, set against the acceptance limits for that product. Buyers use the certificate to confirm a material meets its specification before the material goes into production.

What a COA contains

Formats vary by manufacturer, but a usable certificate generally carries these fields:

Common parameters include assay, identification, moisture or loss on drying, pH of a solution, insoluble matter, and specified impurities such as chloride, sulfate or heavy metals. Which parameters appear depends on the product’s specification, and a test that is not listed should not be assumed to have been run.

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How buyers read one in five minutes

1. Match identity. Product name, grade and code against the order. Similar names can hide different grades.
2. Match the lot. The lot on the COA should equal the lot on the label. A COA for a different lot says nothing about the material in hand.
3. Read the limits. Each limit is a minimum, a maximum or a range.
4. Compare results to limits. If the limit is an assay of at least 99.0% and the result is 99.4%, the lot conforms. Buyers repeat this comparison for every line, not just assay.
5. Check methods, units and dates. Units should match expectations and the lot should sit within its retest date.
6. Escalate gaps. A missing result, an out-of-limit value or a lot mismatch is a hold rather than a judgment call, and the supplier is the next call before use.

Illustrative example, not a real lot.

Common COA Pitfalls

• "Typical" values. A spec sheet shows what the product usually tests at. A COA shows what this lot tested at.
• Pass/fail with no numbers. Numeric values make lot-to-lot trending possible wherever the method produces one.
• Less-than results. A result such as <0.001% means below the method’s reporting limit, not zero.
• Whose results are these? A certificate may be issued by the manufacturer or by another party in the supply chain. Confirming the issuer named on the certificate shows whose testing the numbers represent.
• Wrong scope. A COA that is perfectly correct can still omit the one impurity a given process cares about.

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How we handle COAs at Allan Chemical

We don’t repackage. Material ships in sealed original containers, so the lot number on the label stays matched to the lot-specific COA. Lot on the label and lot on the certificate stay the same. Our Potassium Bromide and Ethylenediaminetetraacetic Acid (EDTA) Disodium Salt pages are examples of listings where the grade is shown on the page and the lot COA and SDS are available on request. Allan Chemical is also International Organization for Standardization (ISO) 9001:2015 certified. For how the lot link supports recalls and investigations, see What Is Chemical Traceability?.

COA, SDS, specification and technical data sheet: what does each tell you?

Buyers typically want the COA and the SDS together: the COA describes the lot, and the SDS describes the product.

Questions buyers ask chemical suppliers

• Is the COA lot-specific, and who issued the certificate?
• Will the lot on the COA match the lot on the container received?
• Which parameters and methods are reported?
• How does the supplier handle an out-of-specification result or a documentation error?
• Does the supplier repackage, and if so, how is the lot carried over?

How COAs are used across industries

When a COA does not conform

1. Place the lot on hold. Many teams label the lot as on hold so the material is not used by accident.
2. Contact the supplier with the lot number and the specific result.
3. Decide whether the deviation matters for the use. A moisture result slightly above the limit may be harmless in one process and significant in another, and the decision-maker is worth writing down.
4. Record the outcome: release, return or reject, plus any corrective action.

Teams commonly keep COAs for at least as long as the material, or the finished products made from the material, are in circulation, and file each certificate so the certificate can be found from a lot number alone. A COA that cannot be found is worth little in an investigation.

Electronic COAs

COAs often arrive as PDFs or through supplier portals, which makes retrieval and filing by lot easier. The same checks apply to a digital certificate as to a paper one: a matching lot number, the issuer’s own version rather than a retyped copy, and storage where the quality team can find the file from a lot number alone. Where a system captures COA data as fields, a second person comparing the transcription against the original adds confidence.

How can companies request a COA from Allan Chemical?

Send us the product name, grade, quantity and, if a shipment has already arrived, the lot number printed on the container. We then send the lot COA together with the SDS and specification. When a quality system calls for particular parameters or test methods, mentioning them before ordering lets us review them against the lot’s certificate. Contact Us to get started, browse by category, for example Laboratory Reagents, Biochemicals, Catalysts & R&D, or see all products.

FAQs

What does COA stand for?

Certificate of Analysis. A COA reports the test results for a specific batch or lot of a product against its specification.

Does Allan Chemical provide Certificates of Analysis?

Yes. Allan Chemical ships material in sealed containers with the lot number on the label, and a lot-specific COA is available for the lot you receive. Contact Us with the product and lot you need.

Does a COA guarantee purity?

No. A COA reports results only for the tests listed. A parameter that is not on the certificate was not reported, so assuming that parameter was within limits is not supported.

How long do companies keep a COA?

Typically at least as long as the material or the products made from the material are in circulation. Quality systems and product-specific requirements may call for longer retention, so many teams confirm the period with their quality group.

What is a retest date?

The date after which the issuer recommends re-evaluating the material before use. Buyers compare the retest date on the COA with their own acceptance window.

What does “<0.001%" on a COA mean?

The result was below the limit the method can report. A less-than result does not mean the substance is absent.

Do buyers still test incoming material when a COA is on file?

That depends on risk. Many buyers run an identity check on every lot and add full testing for critical materials or new suppliers.

Related Reading

• Understanding Chemical Grades: ACS, USP, FCC, and Electronic Grade
• Chemical Quality and Purity: Why They Matter in Pharmaceutical Production
• What Is Chemical Traceability and Why Does It Matter?
• How Supplier Qualification Helps Reduce Chemical Procurement Risks

References

External sources

1. International Pharmaceutical Excipients Council (IPEC): Certificate of Analysis Guide for Pharmaceutical Excipients (free PDF)
2. National Institute of Standards and Technology (NIST): Standard Reference Materials and their certificates
3. International Organization for Standardization: ISO 9001:2015 Quality Management Systems, Requirements

This article is for general information and sourcing guidance. Please consult the current official product specification and a qualified professional for your specific application.