[Meta] the Medutest rule is doing its job and people should stop complaining
the Medutest rule is doing its job and people should stop complaining. This affects how posts get sorted and removed, so it belongs in the open.
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.
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.
How to build a series that means something, if you are going to spend money on testing anyway.
Three tests on one lot tells you about your measurement. Three tests on three lots, spread over a year, tells you about a process. The second is the one worth paying for and it costs the same.
Buy small, keep the batch numbers, send one vial per lot, and post each one with the claim next to it. After four or five you have something no individual review can give you: a band, a direction and a date range. That is what the source pages are made of.
Research-use-only material is not approved for human use and nothing here should be read as a recommendation to use it.
best — the order this archive was captured in
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.
Retitled — the original stated a discrepancy the numbers do not show.
If the report gives a mass spectrum as well as UV purity, say so.
This is why the template has a batch field. Without it the result is about a vial nobody can identify.
Correction: that is the claimed figure, and the measured one is the higher of the two in your own screenshot.
That service reports area percent by default. Worth stating, since the thread has been comparing it to a mass figure.
area percent unless the report says otherwise
Did the vial lot match the paperwork lot?
Do you have the trace, or only the summary?
split a vial across two services once and you will never argue about ground truth again
Small fix — same supplier, different lot. The two rows in the log are not the same batch.
First result I ever posted here got asked for the batch number and the claim. Fair, and my posts have been better ever since.
First result I ever posted here got asked for the batch number and the claim.
Disagreeing with this line: that gap is ordinary variance, not a contradiction between the lab and the certificate.
Agreed on quoting the claim alongside the result. Half the arguments here are two people comparing to different reference numbers.
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a result with no batch number is about a vial nobody can identify
results without method are gossip with decimals
Yes. Two services on the same batch is the strongest thing an individual member can produce, and it is not expensive.
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
Right, and a point or two between services is ordinary. It is agreement, and every month somebody posts it as a scandal.
A series across separate lots estimates a process. Repeat tests on one lot estimate the measurement. Both are useful and they answer different questions.
Area percent or net peptide content?
Disagree that this is a discrepancy. 97.6% against a claimed 97.0% is inside ordinary inter-lab variance in either direction.
Disagree that this is a discrepancy.
Agreed — and two services on one batch is the strongest thing any of us can produce individually.
WXT came back 99.1% on a claimed 98.5%, which is agreement not a discrepancy
- 1Agreed on quoting the claim alongside the result. Half the arguments here…12 comments in this branch · started by u/valeria_girard
- 2If the report gives a mass spectrum as well as UV purity, say so. Identity…11 comments in this branch · started by u/tuva_kirchner