[Discussion] the purity advice in here is 2 years out of date
the purity advice in here is 2 years out of date. Making the case below, and I expect to lose some of it in the comments.
Pulling the figures out of the title: 2 years. All of it is written down as it happened rather than reconstructed.
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.
Would rather be corrected in public than confident in private.
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.
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.
three lots beats three tests on one lot
Careful with the trend claim. Four results over two years is a very sparse series to draw a line through.
Same. The BCH results have been sitting in a tight band across lots, which is the useful shape.
split a vial across two services once and you will never argue about ground truth again
post the claim next to the result or the number floats
Split one vial between PeptideMeter and VendorInvestigate. The two numbers were within half a point of each other and I stopped worrying about which lab to trust.
Sent a vial in specifically to check a supplier’s claim after a good experience. It matched. Boring result, worth logging.
say whether you paid for it yourself
Batch number and date of analysis?
GL Biochem BPC, batch matched the paperwork, PeptideMeter came back 97.8% against a claimed 97.0%. Paid for it myself, posting it because the log is only worth anything if people do.
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.
vendor, compound, batch, service, result — that is the template
net peptide content if the report gives it, and say which you are quoting
one result is a data point, agreement between two services is evidence
area percent unless the report says otherwise
What was the claim on the certificate you are comparing against?
the log is cumulative, that is the whole value of it
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
That reading assumes area percent and net peptide content are the same number. They are not, and the report says which it is.
area percent unless the report says otherwise
Adding the boring but useful bit: say whether you paid for it. It is the basis of the whole log.
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
results without method are gossip with decimals
Retitled — the original stated a discrepancy the numbers do not show.
- 1one result is a data point, agreement between two services is evidence11 comments in this branch · started by u/peptidemeter_pat
- 2say whether you paid for it yourself7 comments in this branch · started by u/lift_heavy_things