Specification in the result column: why that is a meaningful error posts 121–130

Helpful, and easy to find again, which is half of what a good reply is.

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.

Adding it because I spent an afternoon working it out and nobody should have to twice.

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.

I would not lead a decision with this, but I would not ignore it either.

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 my reading. Someone else read the same page differently and was reasonable.

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 where my knowledge stops and I would rather mark the edge than blur it.

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 is what the documentation says. What happens in practice is usually close.

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.

The claim is narrower than it sounds, and deliberately so.

Post #127 is the version of this I will quote in future. One addition.

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.

"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.

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

A test date preceding a manufacturing date is a clerical error until somebody explains otherwise, and asking is cheap. Most such things are transcription.

I would be glad to be shown a cleaner way of putting this.