How to Read a Certificate of Analysis (CoA)
What a CoA is, the fields that matter, and the red flags to check before you accept a chemical shipment.
A Certificate of Analysis (CoA) is a batch-specific document in which a manufacturer states the test results for a given lot of material against a defined specification. In one page it answers the only question that matters at goods-in: does this exact batch meet what I ordered? Reading it well takes two minutes and prevents most quality disputes.
What a CoA is — and isn't
A CoA reports measured results for one batch against a named standard (for example a pharmacopoeia monograph or an in-house specification). It is not a safety document and not a generic product sheet: the values are specific to the lot number printed on it. If the batch number on the drum doesn't match the batch number on the CoA, you don't have a CoA for what's in front of you.
Anatomy of a CoA
| Field | What it tells you | What to check |
|---|---|---|
| Product name & CAS | The substance identity | Matches your order and label exactly |
| Batch / Lot number | Which lot this certifies | Matches the container in hand |
| Specification / grade | The standard tested against | The grade you actually need (e.g. USP, BP, EP) |
| Assay | How much active is present | Within the stated limits (e.g. 99.0–101.0%) |
| Impurities | Related substances, total impurities | Each below its limit |
| Water / loss on drying | Moisture content | Within spec, especially for hygroscopic solids |
| Residual solvents / heavy metals | Process and elemental residues | Below the relevant limits |
| Manufacture & retest dates | Age and re-evaluation point | Material is in date for your use |
| Authorised signatory | QC release | Signed/approved by the quality function |
Red flags to check
- Mismatched batch numbers between the CoA, the label and your records.
- "Conforms" with no number. A real CoA shows measured results, not just a pass/fail tick, for quantitative tests.
- No specification named. A result of "99.2%" means little without the limit it's judged against.
- Missing retest or expiry information for materials that degrade.
- No signatory or release statement from the quality function.
CoA vs SDS — don't confuse them
A CoA certifies quality for one batch; a Safety Data Sheet (SDS) describes hazards and safe handling for the substance in general. You need both: the SDS to handle the material safely, the CoA to confirm the batch you received is the batch you ordered. They serve different purposes and are not substitutes.
The practical takeaway
Treat the CoA as a contract for the lot: identity, grade, assay and impurity results, tied to a batch number you can verify on the container. If anything is missing or mismatched, quarantine and query before use.
Every order from Tech Serve Solutions ships with a Certificate of Analysis, to USP, BP and EP grade where applicable. Browse the catalog, check a CAS number, or request a quote and tell us the specification you need to meet.
Frequently asked questions
What is a Certificate of Analysis?
A batch-specific document in which the manufacturer reports the measured test results for one lot of material against a named specification, confirming that particular batch meets the agreed quality.
What is the difference between a CoA and an SDS?
A CoA certifies the quality of a specific batch (assay, impurities, identity). An SDS describes the substance's hazards and safe handling in general. You need both — they are not interchangeable.
What should I check first on a CoA?
That the batch/lot number on the CoA matches the container in hand, and that the product name and CAS number match your order. Then confirm each result is within its stated limit.
Is 'conforms' enough on a CoA?
Not for quantitative tests. A proper CoA shows the measured value and the limit it's judged against, not just a pass/fail statement.
Does every order come with a CoA?
From Tech Serve Solutions, yes — a Certificate of Analysis accompanies every order, to USP, BP and EP grade where applicable.
