[Lab] WXT BPC — PeptideMeter came back 97.2% against a claimed 97.0%
Short version of the title, which is already short: WXT BPC — PeptideMeter came back 97.2% against a claimed 97.0%. Longer version underneath.
Numbers, in the order they matter: 97.2% and 97.0%.
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.
Screenshot none of this. Read the whole thread, including the parts where I am told I am wrong.
- WXWXT source pageWuXi TIDES (WuXi AppTec Testing Division) · Wuxi · 92% here, rank 14 · shop at wuxitides.net →
nofollow and sponsored; nobody here is paid for it.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.
Yes. Two services on the same batch is the strongest thing an individual member can produce, and it is not expensive.
Area percent or net peptide content?
That service reports area percent by default. Worth stating, since the thread has been comparing it to a mass figure.
post the claim next to the result or the number floats
if you are going to test, test the thing you actually received
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.
What was the claim on the certificate you are comparing against?
Nudging rather than removing: the standard template is in the sidebar and this post is missing the batch field.
Is that the same lot as the one in the thread from last month?
A series across separate lots estimates a process. Repeat tests on one lot estimate the measurement. Both are useful and they answer different questions.
results without method are gossip with decimals
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.
Agreed — the template exists because a result without the batch and the claim is unanchored.
Push back: three tests on one lot is one lot. It tells you about that lot and almost nothing about the next one.
[removed by moderator]
Correcting myself: I quoted net peptide content against somebody else’s area percent. Not a comparison.
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.
Cosigning on saying who paid. It is the whole basis on which this log is worth anything.
net peptide content if the report gives it, and say which you are quoting
Not convinced by the comparison. Different services, different gradients, and you are treating one as ground truth.
- 1Chain of custody is why member-funded testing is worth more than a supplied…7 comments in this branch · started by u/wholesome_lurker
- 2Push back: three tests on one lot is one lot. It tells you about that lot…7 comments in this branch · started by u/refund_ledger