[2026 update] A report I filed that turned out to be wrong, and the correction

On the subject in the title: A report I filed that turned out to be wrong, and the correction Working notes rather than a conclusion.

Structured report rather than an opinion, following the format the maintainers asked for.

• Compound: semaglutide
• Independent testing: VendorInvestigate
• Method as reported: reversed-phase HPLC, 280 nm
• Result: 98.8% area
• Certificate figure for the same lot: 98.2%

I am not drawing a conclusion about the supplier from one lot and I would ask that nobody else does either. I am adding a data point to a record.

Dosing and purity: a vial that is 99% pure might contain 80% of its label claim if the other mass is water, counter-ion, and excipient. Purity and content are different. Both matter for different reasons.

The variance between people here is larger than the effect being discussed.

Adding the measurement that post #2 says would settle it.

Reports of ordinary results are more valuable than reports of remarkable ones, precisely because only the remarkable ones get posted elsewhere.

A difference inside method repeatability is not a disagreement. Saying so in your own report prevents somebody else reading it as one.

The maintainers will ask for missing fields rather than rejecting a report. Filling them in afterwards is normal and nobody minds.

Someone should write this up properly, and it should probably not be me.

I had written a reply contradicting post #4 and deleted it. Here is what survived.

Comparing your result to somebody else's on a different lot is not a comparison of suppliers. Lot is the unit and it should be in every report.

Take it as a starting point and not as a specification.

Acknowledging rather than arguing. The reasoning holds as far as I can follow it.

Post #6 is right about the mechanism and I think understates the practical bit.

The cost of a submission is worth stating. It is the main reason people do not do this and knowing the figure helps somebody else decide.

Coming back to post #9, because the follow-up matters more than the original answer.

Report the certificate figure alongside the independent one. The comparison is the point and it is the part most often omitted.

Everything in post #9 holds. The case it does not cover is the one I have.

Structured report format: compound, lot, independent testing service, method as reported, result, and the certificate figure for the same lot. One lot is one lot. It becomes a pattern at three or four, and it becomes a disputed record when asked and not explained.

Narrowing post #11, because the general version has more than one answer.

Dosing and purity: a vial that is 99% pure might contain 80% of its label claim if the other mass is water, counter-ion, and excipient. Purity and content are different. Both matter for different reasons.

Where you have no independent result, a documentation report is still worth filing: what the certificate contained, what it omitted, and how fast a request was answered.

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

Date the report: when the analysis was done matters. Material can degrade in storage. A report from two years ago is still useful but is not evidence about the current state of the same supplier's stock.

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