The sample is not the batch
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.
Vendors
Page 8 of 48 of this archive, newest first.
Why summer is a documented quality problem in this trade
The route did not close because of a rule about peptides.
A supplier suspends shipping to Singapore after 23 consecutive customs detentions
The route did not close because of a rule about peptides.
Why summer is a documented quality problem in this trade
The route did not close because of a rule about peptides.
A supplier suspends shipping to Norway after 5 consecutive customs detentions
The route did not close because of a rule about peptides.
Janoshik result on a Changsha tirzepatide lot lands 0.8 points above the supplier’s stated figure
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
A supplier suspends shipping to New Zealand after 3 consecutive customs detentions
The route did not close because of a rule about peptides.
What changed at WXT in February, and what the company says prompted it
Documentation practice is the only part of vendor quality a buyer can assess before purchase.
Why summer is a documented quality problem in this trade
The route did not close because of a rule about peptides.
HJ names the synthesis and fill sites behind its catalogue
Documentation practice is the only part of vendor quality a buyer can assess before purchase.
What a 9% rise in coupling-reagent prices does to a 5 mg vial
Follow the resin, not the catalogue.
Medutest result on a Shenzhen retatrutide lot lands 2.4 points above the supplier’s stated figure
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
Medutest result on a Xianning survodutide lot lands 4.4 points above the supplier’s stated figure
The report states the gradient, the wavelength and the integration threshold, which is more than most.
What a split-sample exercise can establish, and what it cannot
Duplicate submissions under different names test within-laboratory repeatability, which is a different quantity from between-laboratory reproducibility.
Independent analysis puts a ERP tirzepatide lot at 98.1%, against 95.1% on the certificate
A reminder that a purity figure is the output of a method, and that methods differ.
Why summer is a documented quality problem in this trade
The route did not close because of a rule about peptides.
What a 34% rise in coupling-reagent prices does to a 2 mg vial
Follow the resin, not the catalogue.
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.
A supplier suspends shipping to Argentina after 16 consecutive customs detentions
The route did not close because of a rule about peptides.
WXT names the synthesis and fill sites behind its catalogue
Documentation practice is the only part of vendor quality a buyer can assess before purchase.