PeptideMeter result on a Changsha retatrutide lot lands 3.4 points below the supplier’s figure
A reminder that a purity figure is the output of a method, and that methods differ.
Nikolaj Brandvold
Page 2 of 7 of this archive, newest first.
Archive — page 2
123 piecesIndependent analysis puts a SGN dulaglutide lot at 96.0%, against 93.3% on the certificate
The supplier has not disputed the finding. It has not explained the gap either.
Percentage of loss, absolute kilograms, and the sleight of hand between them
Both the reassuring reading and the alarming reading are supportable from the same tables. This piece sets out which is which.
What Medutest charges to answer the pyrogen question
We submitted vials for endotoxin determination and report the results, the method and the laboratory, because a pyrogen figure without a method is as empty as a purity…
Leucine, isoleucine, and a difference no balance can measure
Stereochemical inversion changes the molecule, changes its biology, and changes its mass by exactly nothing.
We split six vials four ways and posted them
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.
Independent analysis puts a GL Biochem liraglutide lot at 97.5%, against 93.6% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
Independent analysis puts a QSC mazdutide lot at 97.1%, against 93.6% on the certificate
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
A calculation you should do twice and write down once
Every time a vial changes, the conversion must be recalculated. Carrying forward a unit count from the last vial is the single most reliable way to give the wrong dose.
Why the independent testing market grew a chemistry arm and not a microbiology one
The absence of microbiological capability in this market is a commercial fact with a straightforward explanation, and it is worth understanding before blaming anybody for it.
Two sessions a week, and the evidence behind the prescription
Mass and function are different endpoints and training affects them differently. Most coverage treats them as 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.
VendorInvestigate result on a Nantong dulaglutide lot lands 0.9 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
Same mass, different molecule: why identity by mass is not identity
An isoaspartate rearrangement changes the molecule and not the mass. A method that confirms identity by molecular weight alone will report it as the parent compound.
Independent analysis puts a TFC cagrilintide lot at 95.9%, against 95.2% on the certificate
A reminder that a purity figure is the output of a method, and that methods differ.
Janoshik result on a Hangzhou retatrutide lot lands 0.8 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
Independent analysis puts a WWB semaglutide lot at 95.3%, against 94.2% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
Everything on the page, in the order a chemist would read it
The header identifies the batch, the table records the tests, and the footer says who is answerable. Two of the three are usually incomplete.
What VendorInvestigate is able to certify about a sealed vial, and what it is not
Every certificate circulating in this market answers a question about molecules. Almost none answers a question about organisms, pyrogens, or the integrity of the seal.
A reference interval is not a target, and a result outside one is not a diagnosis
Two sources of noise sit under every number: how reproducible the assay is, and how much the analyte varies within the same person on the same day.