Quadrupole, time-of-flight, orbital trap: what each class can and cannot see
Every instrument specification quoted in an advertisement is a best case obtained on a calibration mixture, not on a submitted vial.
Analytics in 2024
Page 9 of 10 of this archive, newest first.
One column, one wavelength, one very large blind spot
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.
Independent analysis puts a QYB survodutide lot at 95.9%, against 94.3% on the certificate
The supplier has not disputed the finding. It has not explained the gap either.
In-use stability is a separate study, and almost nobody has done it
An in-use period is established by a dedicated study on a specific formulation in a specific container at a specific concentration. Borrowing one from a marketed product is…
Independent analysis puts a SSA exenatide lot at 97.3%, against 93.3% on the certificate
The supplier has not disputed the finding. It has not explained the gap either.
Sixteen daltons: methionine, and the easiest degradation to find
Deamidation adds 0.98 daltons. On a low-resolution instrument at incretin molecular weights, that is inside the noise.
Janoshik result on a Qingdao dulaglutide lot lands 3.9 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
Independent analysis puts a SSA semaglutide lot at 98.0%, against 94.0% on the certificate
The supplier has not disputed the finding. It has not explained the gap either.
PeptideMeter result on a Qingdao cagrilintide lot lands 2.2 points below the supplier’s figure
A reminder that a purity figure is the output of a method, and that methods differ.
Set the threshold at a tenth of a per cent and the small impurities vanish
We work through a single chromatogram twice, under two integration conventions, and show where the difference comes from.
Independent analysis puts a MKM survodutide lot at 97.0%, against 95.7% on the certificate
The result is unremarkable. What the report omits is not.
Leucine, isoleucine, and a difference no balance can measure
Deamidation adds 0.98 daltons. On a low-resolution instrument at incretin molecular weights, that is inside the noise.
The retest date and the expiry date are not the same document
A retest date says that material should be re-examined before use. An expiry date says it should not be used. The trade uses the second word for the first concept.
Independent analysis puts a TFC liraglutide lot at 97.8%, against 94.8% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
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.
Mass spectrometry answers a different question, properly
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.
Independent analysis puts a BCH tirzepatide lot at 98.3%, against 94.9% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
A named analyst is the cheapest quality signal in this trade
What the Journal asks when a document arrives unsigned, and what the answers have been.
Independent analysis puts a FGP liraglutide lot at 95.7%, against 95.0% on the certificate
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
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.