[Lab] split one vial across VendorInvestigate and PeptideMeter — 99.1% and 96.8%
The claim in the title is exactly the claim I am making: split one vial across VendorInvestigate and PeptideMeter — 99.1% and 96.8%. Nothing implied beyond it.
Numbers, in the order they matter: 99.1% and 96.8%.
What a result posted here is actually worth, and how to make yours worth more.
A single figure with no batch identifier is about a vial nobody can locate. Add the batch and it becomes about a lot. Add the claimed figure from the certificate and it becomes a comparison. Add the service and the date and it becomes reproducible. Say that you paid for it yourself and it becomes independent.
Five extra fields, thirty seconds of typing, and the difference between a comment and a row in the log that will still be useful in three years.
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
Happy to answer the boring questions. Those are usually the ones worth asking.
best — the order this archive was captured in
Area percent and net peptide content are different measurements and most reports give one. Quote which, or the comparison downstream is meaningless.
Merged with the other thread on the same batch so the results sit together.
three lots beats three tests on one lot
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.
three lots beats three tests on one lot
yara_mensah is right that the band matters more than the peak. Consistency across lots is the finding.
Cosigning on saying who paid. It is the whole basis on which this log is worth anything.
MKM BPC, batch matched the paperwork, VendorInvestigate came back 98.2% against a claimed 98.0%. Paid for it myself, posting it because the log is only worth anything if people do.
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.
one result is a data point, agreement between two services is evidence
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.
a result with no batch number is about a vial nobody can identify
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.
a result with no batch number is about a vial nobody can identify
This is why the template has a batch field. Without it the result is about a vial nobody can identify.
Area percent or net peptide content?
Did the vial lot match the paperwork lot?
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.
Correction: that is the claimed figure, and the measured one is the higher of the two in your own screenshot.
Correction: that is the claimed figure, and the measured one is the higher of the two in your own screenshot.
Disagreeing with this line: that gap is ordinary variance, not a contradiction between the lab and the certificate.
That service reports area percent by default. Worth stating, since the thread has been comparing it to a mass figure.
Small fix — same supplier, different lot. The two rows in the log are not the same batch.
Sent a vial in specifically to check a supplier’s claim after a good experience. It matched. Boring result, worth logging.
Tested three lots over a year rather than three vials from one lot. Cost the same and told me something completely different.
Correcting myself: I quoted net peptide content against somebody else’s area percent. Not a comparison.
Disagree that this is a discrepancy. 99.4% against a claimed 98.5% is inside ordinary inter-lab variance in either direction.
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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 unless the report says otherwise
How many separate lots does your series cover?
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.
Batch number and date of analysis?
- 1Area percent or net peptide content?7 comments in this branch · started by u/refund_ledger
- 2Area percent and net peptide content are different measurements and most…6 comments in this branch · started by u/gustav_cardoso