[Question] how do you actually verify test results
Asking properly rather than in a comment on somebody else’s thread: how do you actually verify test results.
On inter-lab disagreement, which generates more heat here than anything else.
Two services running different gradients, integrating differently, at possibly different wavelengths, will not produce identical numbers on the same material. A point either way is ordinary. Half a point is close agreement.
The productive response to a gap that size is to post both results with both methods and let the log accumulate. The unproductive response is to pick the lower number, call it the truth, and open a dispute. Members have done the first for long enough now that the bands in the vendor tables are genuinely informative.
Inter-lab variance on this assay runs roughly a point either way, driven mostly by gradient and integration. Two results inside that band agree; they do not disagree quietly.
The template is vendor, compound, batch, service, claim, result, and who paid. Every one of those fields exists because a result missing it has been argued about here before.
Happy to answer the boring questions. Those are usually the ones worth asking.
best — the order this archive was captured in
Chain of custody is why member-funded testing is worth more than a supplied certificate: the vial tested is the vial that arrived at a member’s door.
Merged with the other thread on the same batch so the results sit together.
Small fix — same supplier, different lot. The two rows in the log are not the same batch.
Merged with the other thread on the same batch so the results sit together.
This is why the template has a batch field. Without it the result is about a vial nobody can identify.
Tested three lots over a year rather than three vials from one lot. Cost the same and told me something completely different.
Have now spent more on testing than on some of the orders. No regrets — the log is the reason I can buy without agonising.
say whether you paid for it yourself
Fourth lot from the same supplier in the log now and the band has been tight the whole way. That consistency is the actual finding.
Correcting myself: I quoted net peptide content against somebody else’s area percent. Not a comparison.
Sent a vial in specifically to check a supplier’s claim after a good experience. It matched. Boring result, worth logging.
That service reports area percent by default. Worth stating, since the thread has been comparing it to a mass figure.
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
If the report gives a mass spectrum as well as UV purity, say so. Identity and relative quantity are separate claims and the log tracks both.
Not convinced by the comparison. Different services, different gradients, and you are treating one as ground truth.
post the claim next to the result or the number floats
Push back: three tests on one lot is one lot. It tells you about that lot and almost nothing about the next one.