COA versus SDS: Two Documents That Answer Different Questions

A certificate of analysis and a safety data sheet are both supplier documents and they answer different questions. The COA says what a material is and whether this lot met the specification. The SDS says what hazards the material carries and how to handle it. Asking for one when you need the other is the most common documentation error in the trade.

1. The COA

A certificate of analysis is lot-specific. It states the tests performed, the specification limits and the result for that lot, with the batch or lot number, the date and a signature. It is evidence that a specific lot met a specification.

2. The SDS

A safety data sheet is material-specific and covers hazards, first aid, handling, storage, transport classification and regulatory information. It does not state a lot or a result. It is evidence that the material has been classified and that the hazards are communicated.

3. What a buyer needs

A buyer needs the COA to confirm quality and the SDS to confirm handling and transport. A warehouse needs the SDS; a quality team needs the COA. A brand needs both in the product information file for different reasons.

4. What a COA must contain

The product name and the lot number, the tests and methods, the specification limits, the results, the specification reference, the date and the signature. A COA that states “conforms” without the results is a statement, not a certificate.

5. What an SDS must contain

Sixteen sections as defined by the GHS format, with the hazard classification in section two, the composition in section three and the transport information in section fourteen. A shortened SDS is not an SDS.

6. The common substitution

A supplier asked for an SDS may send a COA because that is the document it has on file. A supplier asked for a COA may send a specification sheet, which describes what the material should be rather than what this lot was. Both substitutions look like a response and neither answers the question.

7. Version control

An SDS has a revision date and a version, and a classification can change. A COA belongs to a lot and never changes; a reprinted COA for a different lot with the same numbers is a red flag. Check the lot number against the delivery note.

8. Retention

Keep the COA for each lot used, linked to the batch records. Keep the current SDS for each material and archive superseded versions. The COA is what allows a finished batch to be traced to its materials; the SDS is what allows a handler to be protected.

9. Audit findings

Auditors routinely find COAs with no lot number, SDS documents that are five years old, and specification sheets filed as certificates. Each of these is a documentation gap that becomes a quality problem when a batch fails and the material cannot be traced.

10. Asking correctly

Ask for “the COA for lot X and the current SDS for this material” rather than for “the technical documents”. A precise request gets a precise answer, and the answer is what goes into the file.

11. Where it fits

Documentation runs across the capsule range; the transport detail continues in the SDS transport entry.