One lot is one lot: when a report becomes a pattern — the long version posts 31–60
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Post #30 is right about the mechanism and I think understates the practical bit.
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.
Reports of ordinary results are more valuable than reports of remarkable ones, precisely because only the remarkable ones get posted elsewhere.
Do not adjust a reported figure. Post what the laboratory said and put your interpretation in a separate sentence.
Report the certificate figure alongside the independent one. The comparison is the point and it is the part most often omitted.
Post #34 answers the question as asked. The question underneath it is different.
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.
I would rather be precise about what I do not know than vague about what I do.
Helpful, and easy to find again, which is half of what a good reply is.
Building on post #37 rather than restating it.
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.
If this contradicts something upthread, the upthread version may well be the better one.
Post #36 put the caveat in the right place and I want to underline it.
Do not adjust a reported figure. Post what the laboratory said and put your interpretation in a separate sentence.
Where I part company with post #37, and it is a narrow parting.
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.
I have kept the units in throughout, for the obvious reason.
A difference inside method repeatability is not a disagreement. Saying so in your own report prevents somebody else reading it as one.
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.
Confirming post #44 from a second method, which matters more than confirming it from a second person.
One lot is one lot. It becomes a pattern at three or four, and the record is built to show which of those you are looking at.
Small point, but it is the one that usually catches people.
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.
It is one reading of the data and not the only reasonable one.
Post #49 is right about the mechanism and I think understates the practical bit.
Pattern across lots: a single result is a data point. Three or four results from the same supplier showing a consistent pattern becomes a record worth discussing. Two results that disagree might just be measurement variation.
Reading it again, the caveat matters more than the finding.
Taking post #48 at face value and following it one step further.
Do not adjust a reported figure. Post what the laboratory said and put your interpretation in a separate sentence.
This is the sort of thing the wiki should carry and currently does not.
Collapsed as off-topic by two members at trust level 3 or above
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.
Reading it back, the second half matters more than the first.
The format we ask for is compound, lot, testing service, method as reported, result, and the certificate figure for the same lot. A report missing any of those goes to the discussion rather than the record.
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.
Posted with less confidence than the sentence structure implies.
Date the submission as well as the result. Turnaround is part of what people want to know and it disappears if only one date is recorded.
The short version is the first sentence; the rest is why.
Photograph the vial and the label before opening. It costs ten seconds and it is what turns a report into something checkable.
Answering the question post #54 raises rather than the one it answers.
Reports of ordinary results are more valuable than reports of remarkable ones, precisely because only the remarkable ones get posted elsewhere.