Certificate of Analysis vs SDS: What Each One Proves

A supplier sends over one PDF and calls it "the documentation," and you file it away assuming it covers everything. Then six months later someone asks for the SDS and all you've got is a Certificate of Analysis, or the reverse. These two documents get lumped together constantly, but they answer completely different questions, and a cosmetic file that only has one of them has a real gap.

What a Certificate of Analysis actually is

A CoA is batch-specific. It's the supplier telling you: this particular lot, with this lot number, was tested and it met the following specifications. Think of it as quality control paperwork for one shipment. A CoA for a botanical extract might confirm the extraction ratio, the appearance, the pH, maybe a marker compound's concentration, and confirm it passed microbial testing. It's proof that the batch you received matches what the supplier claims to sell, not a general safety statement about the substance.

If your supplier changes their process, sources from a different farm, or has a batch that's slightly off-spec, that shows up in the CoA for that lot. It's a snapshot, tied to a specific delivery.

What an SDS actually is

A safety data sheet is not batch-specific at all. It's a standardized 16-section document about the substance generally, covering hazard identification, composition, handling and storage, exposure controls, physical and chemical properties, toxicological information, and more. Section 3 is where you find composition, which is useful when you're trying to confirm INCI names or CAS numbers for a raw material. The SDS doesn't change from lot to lot. It describes the substance as a category, not the specific jar sitting in your storage room right now.

Side by side

	Certificate of Analysis (CoA)	Safety Data Sheet (SDS)
Scope	One specific batch or lot	The substance in general
Changes between shipments	Yes, values can shift lot to lot	No, stays the same unless reformulated
Purpose	Confirms batch met spec	Explains hazards, handling, composition
Typical contents	Test results, lot number, pass/fail	16 sections including composition, hazards, storage
Useful for	Quality assurance, traceability	INCI/CAS confirmation, hazard understanding, GMP
Required for every batch	Often yes	No, one per substance is standard

Why you actually need both

For a cosmetic ingredient file to hold up, you generally want the SDS to tell you what the substance is and how it behaves, and the CoA to tell you that the specific batch in your formula met the standard the supplier promised. Relying only on an SDS means you have no batch-level proof that what arrived matches spec. Relying only on a CoA means you may not have the composition detail (CAS number, hazard classification) that a proper ingredient record needs.

This matters more than it seems for carrier oils and botanical extracts specifically, since these are exactly the categories where batch-to-batch variation is real. Two lots of the same cold-pressed oil, harvested months apart, can have measurably different fatty acid profiles even though the SDS describing the general substance hasn't changed at all.

A quick gut check for your files

• If you have an SDS but no CoA for a botanical or natural ingredient, ask your supplier for one, especially for anything with natural variability.
• If you have a CoA but no SDS, you're missing the composition and hazard picture, which matters for GMP recordkeeping (ISO 22716 leans on this kind of documentation) and for confirming INCI/CAS mapping.
• If a document is labeled one thing but reads like the other, don't assume, verify what it actually contains before filing it as either.

Where this connects to your notification

When you're preparing a cosmetic notification, what you actually need is the INCI name, the CAS number, and the concentration for each ingredient, information that generally comes from the SDS and your own formulation records, not from a CoA. The CoA lives in your quality file as proof the batch you used was legitimate, which matters if there's ever a complaint or an audit, but it's not what drives the notification itself. Cosmetic Comply focuses on that INCI and CAS mapping piece when you're filing, so your CoAs can stay where they belong, in your supplier and batch records, rather than getting shoehorned into a filing that doesn't need them.