A grade describes a standard. A Certificate of Analysis describes a batch. Those are different statements, and the gap between them is where most quality disputes start.
When you order USP-grade material you are naming a monograph — a published set of identity tests and limits. When the consignment arrives, the CoA tells you what the material in front of you actually measured against that monograph. It is the only document in the transaction that is about your material rather than about a category.
What is on it
Most certificates carry the same elements, whatever the house style.
Identification of the batch. Product name, CAS number, batch or lot number, manufacturing date, and either a retest date or an expiry date. This is the part people skim and should not.
The specification column. The limits the material was tested against, and — crucially — which authority those limits come from. A CoA that says "Assay: 98.5–101.0%" is only meaningful once you know whether that range is USP's, EP's, or an in-house specification.
The result column. What this batch measured. Numeric results are more useful than "Complies", because a number tells you where in the range the material sits and "Complies" only tells you it is somewhere inside it.
The test list. Typically appearance, identification, assay, loss on drying or water content, residue on ignition or sulphated ash, heavy metals, related substances, and residual solvents. Which of these appear depends on the monograph.
Method references. Pharmacopoeial certificates cite the chapter used — a USP general chapter number, or a Ph. Eur. method reference. Two laboratories using different methods can produce different numbers for the same material, so the method is part of the result.
A release statement, signed or approved by the quality function that issued it.
Four checks worth making
Does the batch number on the certificate match the batch on the drum? It sounds trivial. It is the single most common discrepancy, and it invalidates everything else on the page.
Does the specification column name the standard you ordered against? If you specified EP and the certificate is written against USP limits, the results are real but they do not answer your question. The monographs differ, and a material can satisfy one while sitting outside the other.
Is it a retest date or an expiry date? They are not the same. An expiry date says the material should not be used afterwards. A retest date says it can be requalified by testing and, if it still meets specification, used on. Treating one as the other either wastes good material or uses material you should have rechecked.
Where in the range does the assay sit? A result at the edge of the specification is compliant. It is also a result that will behave differently from one in the middle if your process is sensitive, and it tells you something about consistency across lots that a pass/fail does not.
What a CoA does not tell you
It does not tell you what the remainder is. A 99.5% assay means half a percent of the material is something else, and the certificate only names the impurities the monograph asks about. Two batches can hold the same assay and behave differently in a process because their impurity profiles differ — which is a separate conversation, and one worth having before you qualify a supply rather than after.
It also is not a safety document. Handling, exposure limits and transport classification live on the safety data sheet, which is issued alongside it.
In practice
Ask for the certificate against the batch being supplied, not a specimen from a previous lot. Read the specification column before the result column. And if the material is going into something regulated, have whoever will be accountable for it read the certificate before the container is opened rather than after.