A checklist for reading a certificate in under two minutes — does this still hold?

The arithmetic in post #14 is right; the assumption feeding it is the part to check.

A certificate is a statement by its issuer that a defined test was performed on a defined lot and produced a defined result. That is all it is, and it is not nothing.

I would call that likely rather than established.

A document that puts the specification in the result column has told you the release criterion rather than the measurement. Those are different claims and the difference is the whole point of reading the document.

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

Everything in post #17 holds. The case it does not cover is the one I have.

When method identifiers are missing: "reversed-phase HPLC" is less specific than "reversed-phase HPLC at 214 nm on a C18 column with a 10 to 40% acetonitrile gradient over 20 minutes". The second lets someone reproduce the analysis. The first does not.

Noting that the question and the thing people usually mean by it are different.

"Not less than 98 per cent" is a specification. "98.3 per cent" is a result. A certificate carrying only the first has not told you what was measured.

Two people can read the same figure differently here and both be reasonable.

Peptide content and chromatographic purity are separate determinations and a certificate that reports only one has answered only one question. Content is the one that tells you how much is in the vial.

On post #20 — agreed on the reasoning, with one qualification.

Where two documents for the same lot disagree, the useful question is which was measured and which was transcribed. Most such disagreements are the second.

Post #22 is right about the mechanism and I think understates the practical bit.

The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".

That is what I would do. It may not be what is correct.

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

Same conclusion as the reply above, reached differently, which is mildly reassuring.

Appreciated. The plain phrasing does more work here than a longer post would.

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

The honest answer is that it depends, and here is what it depends on.

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

That has held every time I have looked, which is not the same as always.

Taking post #27 at face value and following it one step further.

The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".

I am not the right person to answer the follow-up to this.

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

The mechanism is plausible, which is not the same as established.