Blind duplicates: what happens when a laboratory does not know it is being watched
Duplicate submissions under different names test within-laboratory repeatability, which is a different quantity from between-laboratory reproducibility.
Independent testing
Page 8 of 27 of this archive, newest first.
Size exclusion sees the thing reversed-phase dissolved
Where two methods disagree, the conservative convention is to report the lower figure. It is not universal, and whether a laboratory follows it belongs on the report.
Reproducibility, measured rather than assumed
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.
How to check a certificate in ten minutes
What each missing test would cost to add, and which of them a buyer should actually want.
Medutest result on a Zhuhai orforglipron lot lands 3.8 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
Medutest result on a Qingdao dulaglutide lot lands 1.4 points below the supplier’s figure
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
What a batch number is supposed to mean
What happens to traceability when bulk material is subdivided, repackaged and relabelled two or three times before sale.
Independent analysis puts a ERP exenatide lot at 95.8%, against 93.5% on the certificate
A reminder that a purity figure is the output of a method, and that methods differ.
Why purity is the cheapest number to flatter
Peptide content, identity, aggregate burden, moisture and endotoxin are all more informative for some purposes. All of them cost more.
Independent analysis puts a KP semaglutide lot at 95.6%, against 94.1% on the certificate
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
Tandem mass spectrometry, and the difference between weighing and reading
The Journal’s standing position: a mass that matches is necessary evidence of identity and nowhere near sufficient.
The badge is about a sample. The listing is about a product.
The Journal does not treat a badge as evidence and states so wherever it reports one.
PeptideMeter result on a Wuhan orforglipron lot lands 2.1 points below the supplier’s figure
The result is unremarkable. What the report omits is not.
How a claim degrades between the bench and the listing
The Journal does not treat a badge as evidence and states so wherever it reports one.
Independent analysis puts a GGPeps tirzepatide lot at 95.4%, against 92.1% on the certificate
A reminder that a purity figure is the output of a method, and that methods differ.
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.
Independent analysis puts a HJ dulaglutide lot at 95.0%, against 93.3% on the certificate
A reminder that a purity figure is the output of a method, and that methods differ.
Repackaging, subdivision, and the batch number that changed hands
A document is only as good as the chain that connects it to the material, and most chains here are two or three links longer than the paperwork admits.
Reading a certificate as a document rather than as a score
Nothing on this page is difficult. It is simply unfamiliar, and unfamiliarity is what makes a weak certificate look like a strong one.
A vial can be 99.4 per cent pure and not sterile in the same afternoon
The Journal has read several hundred certificates from twenty companies. We set out what the documents actually cover, and what a reader is filling in from imagination.