Short answer
A Certificate of Analysis (COA) is the test report for one specific batch. It lists each parameter tested, the specification limit, the actual result and the test method, and it is signed by the supplier's quality team. Check that the batch number matches the label on the packs, that every result sits inside your specification, and that the results are real measurements rather than copied typical values.
Key points
- 01A COA covers one batch. A TDS describes the product in general. An SDS covers safety.
- 02The batch number on the COA must match the drum, bag or IBC label.
- 03Each result should show the method used and fall inside the stated limit.
- 04Identical results across many batches are a warning sign.
COA, TDS and SDS: what's the difference?
| Document | What it covers | Changes with each batch? |
|---|---|---|
| Certificate of Analysis (COA) | Actual test results for one batch | Yes |
| Technical Data Sheet (TDS) | Typical properties, grades, uses and packing | No |
| Safety Data Sheet (SDS) | Hazards, handling, storage, first aid and transport, in 16 sections | No, only when revised |
The parts of a COA
- Supplier name and address, and the product name and grade
- Batch or lot number, which ties the certificate to the physical goods
- Manufacturing date, and an expiry or retest date where relevant
- Test parameters, such as assay, moisture, pH, appearance and impurities
- Specification limits for each parameter, such as minimum 98.0%
- Actual result for each parameter in this batch
- Test method for each parameter: a pharmacopoeia, national standard or in-house method
- A pass or conforms statement, the date, and the signature of the quality person who released it
An example row
Illustrative only. Each product has its own parameters and limits.
| Parameter | Specification | Result | Method |
|---|---|---|---|
| Assay | ≥ 98.0% | 98.6% | Titration |
| Moisture | ≤ 0.5% | 0.21% | Karl Fischer |
| pH (5% solution) | 6.0 – 8.0 | 7.1 | pH meter |
| Appearance | White powder | Conforms | Visual |
Red flags
- The batch number does not match the packs, or there is no batch number at all
- Results are identical from one batch to the next, which suggests copied values
- "Typical" values instead of actual results
- No test method stated for a result
- No date, signature or name of the person who released the batch
- A result outside the limit, but the certificate still says it conforms
What to do on arrival
File the COA against the delivery and compare it with your purchase specification. For critical parameters, retest a sample from the delivery in your own lab or a third-party lab. If you need specific parameters or methods, agree them in the purchase order so they appear on every certificate.
Questions
Also asked.
It should be. A COA describes one batch, so every batch needs its own. Cosmo Chemistry issues the COA and SDS against the specific batch that is packed and shipped.
Yes. Agree the parameters, limits and methods before ordering so the supplier can test and report them for every batch.
A COA reports the actual results of one batch. A TDS gives the product's typical properties and does not change from batch to batch.
