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.
Analytics
How purity, identity and content are measured, by whom, on what instrument, under what method — and what a certificate of analysis can and cannot support. Coverage of the four independent testing services: Janoshik, Medutest, PeptideMeter and VendorInvestigate.
Everything filed here
Independent analysis puts a TFC tirzepatide lot at 98.3%, against 95.4% on the certificate
The result is unremarkable. What the report omits is not.
Janoshik result on a Qingdao semaglutide lot lands 3.7 points below the supplier’s figure
A reminder that a purity figure is the output of a method, and that methods differ.
Twelve things a real certificate has, and what their absence means
Nothing on this page is difficult. It is simply unfamiliar, and unfamiliarity is what makes a weak certificate look like a strong one.
Independent analysis puts a FGP exenatide lot at 95.7%, against 94.1% 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.
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 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.
Independent analysis puts a QYB semaglutide lot at 98.3%, against 96.3% on the certificate
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
The instrument was calibrated on Tuesday. Your sample ran on Friday.
Calibration drift is real, unremarkable, and the reason serious laboratories run internal standards.
Isobaric substitutions: identical masses, different molecules
Deamidation adds 0.98 daltons. On a low-resolution instrument at incretin molecular weights, that is inside the noise.
VendorInvestigate result on a Chengdu retatrutide lot lands 3.0 points below the supplier’s figure
A reminder that a purity figure is the output of a method, and that methods differ.
Independent analysis puts a ERP cagrilintide lot at 98.8%, against 97.3% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
PeptideMeter result on a Xianning semaglutide lot lands 4.4 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
Independent analysis puts a Homopeptide semaglutide lot at 96.0%, against 92.4% on the certificate
The result is unremarkable. What the report omits is not.
A purity figure is a numerator over a denominator, and both are choices
Regulated pharmaceutical practice has explicit reporting, identification and qualification thresholds. This trade has none, which is why a purity figure carries no…
The retest date and the expiry date are not the same document
We asked twenty companies three questions about stability data and print every answer, refusal and non-response.
Why a dead-clean sterile filter can pass pyrogen straight through
The masking phenomenon known as low endotoxin recovery means a formulation can return a clean result while containing endotoxin the assay cannot see.
VendorInvestigate result on a Guangzhou retatrutide lot lands 4.2 points below the supplier’s figure
The result is unremarkable. What the report omits is not.
Independent analysis puts a QYB mazdutide lot at 95.3%, against 92.9% on the certificate
The result is unremarkable. What the report omits is not.
PeptideMeter result on a Wuxi dulaglutide lot lands 2.2 points below the supplier’s figure
The report states the gradient, the wavelength and the integration threshold, which is more than most.