Certificate of analysis checklist
Seven checks you can make on a certificate before paying. Tick them off against the document in front of you.
How to use it
Open the certificate next to this page and work down. Every item is a property of the document, so it is answerable before any money moves and without trusting anyone. Nothing you tick is stored or sent anywhere; the page only counts.
Each check is explained at length, with what it does and does not settle, in our note on verifying a supplier. The abbreviations are defined in the certificate glossary.
A missing line is not automatically a failure
Some fields are optional for good reason. Endotoxin content matters for work with cultured cells and is irrelevant to a chemistry experiment, so its absence is not a gap by itself. What matters is that an unmeasured parameter is described as unmeasured, not implied to be absent.
A specification is not a result
The two look alike on a page and answer different questions. "≥ 99% by HPLC" is the threshold the batch had to meet. "99.2%, measured 14 March, batch CDX-1017" is a measurement of one batch on one day. Only the second describes the material you are buying.
This is not a judgement about any supplier
Every item describes a property of a document, and any supplier can satisfy all seven by producing better documents. That is the point: the checks are about what can be verified, not about who is selling.
Frequently asked questions
What should I check on a peptide certificate of analysis?
That the batch number matches the vial, that a method and a date sit next to every number, that a laboratory is named and the document signed, that identity is reported as well as purity, that net peptide content is separate from chromatographic purity, and that any chromatogram has readable axes.
Why is the batch number the first check?
Because a certificate describes one batch. If the number on the document does not match the number on the label, the document describes different material and nothing else on it applies to your vial.
Is my progress saved?
No. The checkboxes exist only while the page is open and nothing is sent anywhere. Use the print button if you want a copy to carry.
What if the certificate has no endotoxin line?
Not automatically a problem. Endotoxin matters for work with cultured cells and is irrelevant to many chemistry experiments. What matters is that an unmeasured parameter is described as unmeasured, not implied to be absent.
What is the difference between a specification and a result?
A specification is the threshold a batch had to meet, such as ≥ 99%. A result is the value measured for that batch on a given day. Only the result describes the material you are buying.
Does passing all seven mean the material is good?
It means the documentation is checkable, which is a different thing. A document can be complete and honest about a batch that is merely adequate. What the checklist rules out is being unable to tell.