help me understand PeptideMeter, I have read the wiki twice
help me understand PeptideMeter, I have read the wiki twice — that is what I am asking, and I have already read the wiki twice.
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.
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.
TFC BPC, batch matched the paperwork, PeptideMeter came back 98.7% against a claimed 98.0%. Paid for it myself, posting it because the log is only worth anything if people do.
If two or three other people have done the same thing we might actually learn something. Alone it is an anecdote.
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.
Sent a vial in specifically to check a supplier’s claim after a good experience. It matched. Boring result, worth logging.
I would not post that as a finding. It is a single result and the template asks you to say so.
Right, and a point or two between services is ordinary. It is agreement, and every month somebody posts it as a scandal.
This. The trend across separate lots is the number that tells you about a process rather than a vial.
if you are going to test, test the thing you actually received
Push back: three tests on one lot is one lot. It tells you about that lot and almost nothing about the next one.
post the claim next to the result or the number floats
Same. The Homopeptide results have been sitting in a tight band across lots, which is the useful shape.
Did the vial lot match the paperwork lot?
Agreed on quoting the claim alongside the result. Half the arguments here are two people comparing to different reference numbers.
results without method are gossip with decimals
Split one vial between VendorInvestigate and Medutest. The two numbers were within half a point of each other and I stopped worrying about which lab to trust.
Area percent and net peptide content are different measurements and most reports give one. Quote which, or the comparison downstream is meaningless.
WWB came back 99.3% on a claimed 99.0%, which is agreement not a discrepancy
Not convinced by the comparison. Different services, different gradients, and you are treating one as ground truth.
Have now spent more on testing than on some of the orders. No regrets — the log is the reason I can buy without agonising.
What was the claim on the certificate you are comparing against?
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.
That service reports area percent by default. Worth stating, since the thread has been comparing it to a mass figure.
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.
Left up and added to the vendor source page log. Thanks for paying for it and posting it.
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
Correction: that is the claimed figure, and the measured one is the higher of the two in your own screenshot.
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.
Small fix — same supplier, different lot. The two rows in the log are not the same batch.
Correcting myself: I quoted net peptide content against somebody else’s area percent. Not a comparison.
- 1I would not post that as a finding. It is a single result and the template…8 comments in this branch · started by u/coring_the_stopper
- 2Agreed on quoting the claim alongside the result. Half the arguments here…6 comments in this branch · started by u/fatima_wojcik