how much of what we believe about purity actually comes from batch threads
The title is the whole question — how much of what we believe about purity actually comes from batch threads — but here is why I am asking.
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.
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.
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.
Not medical advice, obviously, and nothing here is approved for human use. One person with a spreadsheet.
best — the order this archive was captured in
Date of analysis anchors the result to a manufacturing period. A two-year-old result is evidence about two years ago and should be read that way.
Area percent and net peptide content are different measurements and most reports give one. Quote which, or the comparison downstream is meaningless.
How many separate lots does your series cover?
Disagree that this is a discrepancy. 99.3% against a claimed 98.5% is inside ordinary inter-lab variance in either direction.
Disagree that this is a discrepancy.
yara_bakken is right that the band matters more than the peak. Consistency across lots is the finding.
This. The trend across separate lots is the number that tells you about a process rather than a vial.
a result with no batch number is about a vial nobody can identify
That service reports area percent by default. Worth stating, since the thread has been comparing it to a mass figure.
a result with no batch number is about a vial nobody can identify
Adding the boring but useful bit: say whether you paid for it. It is the basis of the whole log.
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.
one result is a data point, agreement between two services is evidence
date of analysis matters as much as the number
Retitled — the original stated a discrepancy the numbers do not show.
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.
Inter-lab variance on this assay runs roughly a point either way, driven mostly by gradient and integration.
Agreed — and two services on one batch is the strongest thing any of us can produce individually.
Agreed on quoting the claim alongside the result. Half the arguments here are two people comparing to different reference numbers.
the log is cumulative, that is the whole value of it
area percent unless the report says otherwise
Yes. Two services on the same batch is the strongest thing an individual member can produce, and it is not expensive.
Batch number and date of analysis?
Batch number and date of analysis?
Disagreeing with this line: that gap is ordinary variance, not a contradiction between the lab and the certificate.
First result I ever posted here got asked for the batch number and the claim. Fair, and my posts have been better ever since.
three lots beats three tests on one lot
Small fix — same supplier, different lot. The two rows in the log are not the same batch.
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.
A series across separate lots estimates a process. Repeat tests on one lot estimate the measurement. Both are useful and they answer different questions.
say whether you paid for it yourself
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.
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
A series across separate lots estimates a process.
This is why the template has a batch field. Without it the result is about a vial nobody can identify.
- 1This. The trend across separate lots is the number that tells you about a…12 comments in this branch · started by u/peptidemeter_pat
- 2area percent unless the report says otherwise7 comments in this branch · started by u/lift_heavy_things