someone explain PeptideMeter to me like I have not read a paper in years
someone explain PeptideMeter to me like I have not read a paper in years. Searched first, found three threads that contradict each other, hence the post.
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.
First result I ever posted here got asked for the batch number and the claim. Fair, and my posts have been better ever since.
That is everything I have. The rest is opinion and I have tried to keep it out.
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.
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.
if you are going to test, test the thing you actually received
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.
post the claim next to the result or the number floats
Split one vial between Janoshik 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.
Same. The KP results have been sitting in a tight band across lots, which is the useful shape.
vendor, compound, batch, service, result — that is the template
Area percent or net peptide content?
Is that the same lot as the one in the thread from last month?
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.
the trend across lots is worth more than any single figure
Left up and added to the vendor source page log. Thanks for paying for it and posting it.
That reading assumes area percent and net peptide content are the same number. They are not, and the report says which it is.
Which service, and did you pay for it yourself?
Correction: that is the claimed figure, and the measured one is the higher of the two in your own screenshot.
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
one result is a data point, agreement between two services is evidence
results without method are gossip with decimals
split a vial across two services once and you will never argue about ground truth again
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
inter-lab variance runs a point or two, plan your outrage accordingly
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.
Have now spent more on testing than on some of the orders. No regrets — the log is the reason I can buy without agonising.
Cosigning on saying who paid. It is the whole basis on which this log is worth anything.
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.
- 1What a result posted here is actually worth, and how to make yours worth…8 comments in this branch · started by u/aussie_pbs_watch
- 2Split one vial between Janoshik and VendorInvestigate. The two numbers were…6 comments in this branch · started by u/camila_mensa