Notes from the bench.

It is the most common message a peptide supplier receives, and it almost always says the same thing: the vial looks empty. Sometimes there is a thin film. Sometimes a small disc has come loose and is rattling. Sometimes genuinely nothing is vi

Reconstitution is one equation. Almost every error made with it is a units error, and almost every units error is made in the same three places. Here is the arithmetic in full, and where it goes wrong. The equation Concentration is mass di

Every reconstitution guide says do not shake the vial. Very few say why, and a rule without a reason is a rule people break when they are in a hurry. Here is the mechanism. Peptides collect at surfaces Most peptides have both hydrophilic a

“Store cold, keep it dry, keep it dark” is good advice and a poor explanation. Peptides do not degrade generically; they degrade by specific chemical routes, and which routes are open depends on which residues are in the sequence.

Peptide names are written in a shorthand that assumes you already know it. Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 is a complete and precise description of a molecule, and it is unreadable until someone explains the notation. Here is the w

Two numbers describe a vial of lyophilised peptide, they mean entirely different things, and almost every supplier quotes only the one that flatters them. This is the distinction worth understanding before you compare any two certificates. P

Every certificate we issue carries two measurements. They are not redundant, and neither one substitutes for the other. Here is what each instrument is actually doing, and why a certificate carrying only one of them has verified half of what i

A certificate of analysis is the only document standing between a claim and a measurement. It is also, in this industry, the document most often faked, borrowed, or quietly detached from the material it is supposed to describe. Here is what a

Almost every supplier in this industry says the same four words: third-party tested. Far fewer will say when. The order of operations is the part that decides whether the phrase means anything, and it is the part nobody advertises. Two ways