What a laboratory knows about the material it receives
A result on one vial generalises to a batch only if the vial was drawn in a way that makes it representative — and nobody records how it was drawn.
PeptideMeter
Page 4 of 8 of this archive, newest first.
A tested vial is evidence about a vial
A result on one vial generalises to a batch only if the vial was drawn in a way that makes it representative — and nobody records how it was drawn.
The submitted sample: the weakest link in the whole system
Every third-party report in this market describes a sample somebody chose to send. That choice is outside the laboratory’s control and outside its records.
Assay against a standard, or area per cent: two different questions
We asked the four independent testing services what standards they run against and what suitability criteria they apply. The answers are printed.
From vial to bench: what is recorded and what is assumed
The condition on arrival is recorded by some services and not others, and it is one of the more informative lines in a report.
The figure of merit this trade chose, and the four it did not
A market that competes on one measurement will optimise that measurement. There are legitimate ways to raise a purity figure that involve no change to the product at all.
Custody, condition and the temperature nobody logged
The condition on arrival is recorded by some services and not others, and it is one of the more informative lines in a report.
Six words a verification badge would need to mean anything
A badge asserts that something was tested. It does not assert what, when, on whose sample, by what method, or whether the lot on sale is the lot that was tested.
The column is a choice, and it is not a small one
We set out the parameters a method disclosure would contain, all of which are known to whoever ran the sample and none of which is commercially sensitive.
Six words a verification badge would need to mean anything
The Journal does not treat a badge as evidence and states so wherever it reports one.
What a laboratory knows about the material it receives
A result on one vial generalises to a batch only if the vial was drawn in a way that makes it representative — and nobody records how it was drawn.
What counts as total, and who decided
We work through a single chromatogram twice, under two integration conventions, and show where the difference comes from.
Why purity is the cheapest number to flatter
The Journal has read several hundred certificates from twenty companies. The number is almost always there; the method behind it almost never is.
Mass spectrometry answers a different question, properly
The most useful single addition to any purity determination is a second separation under a different pH or on a different stationary phase, and the second-most useful is a…
How a claim degrades between the bench and the listing
Every step between the laboratory report and the product page removes information, and the badge is the last step.
A tested vial is evidence about a vial
Chain of custody, in a regulated setting, begins at sampling. Here it begins when the package arrives.
The conservative convention: report the lower of two numbers
An orthogonal method separates on a different physical principle, so that species co-eluting in the first are likely to resolve in the second. Two runs of the same method at…
The named comparison we promised two years ago
Two years ago we ran an anonymised version of this comparison and promised a named one. This is it, with every method printed in full.
The sample is not the batch
Chain of custody, in a regulated setting, begins at sampling. Here it begins when the package arrives.
The submitted sample: the weakest link in the whole system
The condition on arrival is recorded by some services and not others, and it is one of the more informative lines in a report.