Before anything is weighed, the peptide has to be charged
A brief and unromantic tour of the interface between a liquid sample and a vacuum.
Independent testing
Page 16 of 27 of this archive, newest first.
PeptideMeter result on a Tianjin semaglutide lot lands 1.1 points below the supplier’s figure
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
An interlaboratory comparison nobody had run
Duplicate submissions under different names test within-laboratory repeatability, which is a different quantity from between-laboratory reproducibility.
Independent analysis puts a WXT exenatide lot at 97.4%, against 93.5% on the certificate
The supplier has not disputed the finding. It has not explained the gap either.
Janoshik result on a Suzhou mazdutide lot lands 4.0 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
Why a dead-clean sterile filter can pass pyrogen straight through
The limit for a parenteral product is calculable from the dose and the body weight in two lines. Almost nobody in this trade performs the calculation.
Independent analysis puts a GGPeps tirzepatide lot at 96.6%, against 93.7% on the certificate
The result is unremarkable. What the report omits is not.
Who signed this, and what did they undertake by signing it
What the Journal asks when a document arrives unsigned, and what the answers have been.
Two decimal places on a single injection is a rhetorical choice
A result without a specification is a number. A specification without a result is a promise. Certificates in this market frequently carry one and not the other.
Independent analysis puts a WWB survodutide lot at 99.0%, against 97.4% on the certificate
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
Janoshik result on a Suzhou semaglutide lot lands 0.7 points below the supplier’s figure
The result is unremarkable. What the report omits is not.
Why a result on one vial says less than the trade needs it to
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 word “confirmed” is doing an enormous amount of work on this certificate
An intact mass measurement establishes elemental composition, at best. The number of distinct sequences consistent with a given composition is astronomically large.
Why the compendial sterility test is a rejection test and nothing more
The compendial sterility test cannot demonstrate that a batch is sterile. It can only fail a batch that is grossly contaminated. Everything else is process validation.
LAL, kinetic chromogenic, recombinant factor C: three ways to the same figure
Three compendial method families are in routine use and a fourth, based on a recombinant enzyme rather than crab lysate, is now compendial in its own right.
Independent analysis puts a SSA survodutide lot at 97.1%, against 96.4% on the certificate
The result is unremarkable. What the report omits is not.
Independent analysis puts a QSC exenatide lot at 97.5%, against 96.7% on the certificate
The supplier has not disputed the finding. It has not explained the gap either.
Everything a buyer assumes has been checked, ranked by whether it has
The absences are not concealment. They are the form the trade settled on, and no buyer has ever objected.
At 214 nanometres you see every peptide bond. At 280 you see three residues.
Area per cent silently assumes that every species in the sample absorbs as strongly per unit mass as the parent. For peptide impurities that assumption is usually wrong, and…
The empty half of every certificate of analysis
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.