test results — 20 things I got wrong before I got it right
Thinking out loud about this: test results — 20 things I got wrong before I got it right.
First result I ever posted here got asked for the batch number and the claim. Fair, and my posts have been better ever since.
Have now spent more on testing than on some of the orders. No regrets — the log is the reason I can buy without agonising.
Sent a vial in specifically to check a supplier’s claim after a good experience. It matched. Boring result, worth logging.
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.
Disagree that this is a discrepancy. 98.0% against a claimed 97.5% is inside ordinary inter-lab variance in either direction.
Push back: three tests on one lot is one lot. It tells you about that lot and almost nothing about the next one.
What was the claim on the certificate you are comparing against?
Not convinced by the comparison. Different services, different gradients, and you are treating one as ground truth.
Careful with the trend claim. Four results over two years is a very sparse series to draw a line through.
Careful with the trend claim.
Agreed — and two services on one batch is the strongest thing any of us can produce individually.
post the claim next to the result or the number floats
Agreed — and two services on one batch is the strongest thing any of us can produce individually.
stubborn_batchlist_only is right that the band matters more than the peak. Consistency across lots is the finding.
I would not post that as a finding. It is a single result and the template asks you to say so.
Left up and added to the vendor source page log. Thanks for paying for it and posting it.
say whether you paid for it yourself
Correction: that is the claimed figure, and the measured one is the higher of the two in your own screenshot.
Correcting myself: I quoted net peptide content against somebody else’s area percent. Not a comparison.
GL Biochem came back 99.1% on a claimed 99.0%, which is agreement not a discrepancy
That reading assumes area percent and net peptide content are the same number. They are not, and the report says which it is.
vendor, compound, batch, service, result — that is the template
area percent unless the report says otherwise
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
Yes — date of analysis, because a result from two years ago describes a different manufacturing month.
split a vial across two services once and you will never argue about ground truth again