What a certificate commits its issuer to — the long version

Asking directly, because I could not find a straight answer: What a certificate commits its issuer to — the long version

A documentation question rather than an analytical one.

I have a certificate in front of me that reports a purity figure, names a technique, gives a wavelength, and stops. No gradient, no column, no injection volume, no chromatogram.

What can I legitimately conclude from that document? My instinct is "almost nothing, but not literally nothing", and I would like to know where the people who read these professionally draw the line.

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.

This is the sort of thing that ought to be settled and apparently is not.

The arithmetic in post #2 is right; the assumption feeding it is the part to check.

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.

This is the sort of thing the wiki should carry and currently does not.

Answering the question the opening post raises rather than the one it answers.

"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.

Taking post #2 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".

Residual solvent screening is not standard on these documents and its presence is a signal about the manufacturer's own systems rather than about the vial.

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 would hold that lightly until someone with a larger sample weighs in.

Everything in post #4 holds. The case it does not cover is the one I have.

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.

Two sources, same conclusion, and I could not rule out that one copied the other.

This follows post #6 rather than contradicting it.

Reading old certificates: if a certificate is dated years ago, the lot it describes might be old. That is not automatically a problem but it is worth noting. Fresh testing on the current lot is stronger than old testing on an older lot.

A single observation, in a thread that deserves better than single observations.

Worth separating two things that post #8 runs together.

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.

I would put the burden of proof on the interesting explanation, not the dull one.

I had written a reply contradicting post #7 and deleted it. Here is what survived.

A certificate of analysis 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. What makes it usable: lot identifier matching the container, test date, method identification specific enough to reproduce, the actual result as a number, and the acceptance criterion stated separately from the result.

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.

That is the version I use. It may not be the version that is correct.

Fair, and the limits you put on it are the part I will remember.