Same material, different gradients, different answers
Duplicate submissions under different names test within-laboratory repeatability, which is a different quantity from between-laboratory reproducibility.
Peptide content
The fraction of a vial’s mass that is actually peptide — a different question from purity, and rarely reported.
One method is one opinion
Aggregates dissociate in the mobile phase and are recorded as monomer. Only a size-based separation reports them.
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.
What a laboratory knows about the material it receives
Chain of custody, in a regulated setting, begins at sampling. Here it begins when the package arrives.
Disregard limits: what a regulated laboratory does with a tiny peak
Baseline placement under a tailing peak is a judgement call with a direct effect on the area. It is one of the few places where two competent analysts genuinely disagree.
Six words a verification badge would need to mean anything
What a verification mark would have to carry to be checkable: a date, a lot, a method, a submitter and a link to the report.
From vial to bench: what is recorded and what is assumed
The condition on arrival is recorded by some services and not others, and it is one of the more informative lines in a report.
Five things a purity figure cannot tell you
Aggregates dissociate in the mobile phase and are recorded as monomer. Only a size-based separation reports them.
Same material, different gradients, different answers
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.
Same material, different gradients, different answers
The Journal submitted split samples from single lots to three assay services, under names unconnected to this publication, and published each method alongside each result.
How a release document is put together in a regulated plant
Nothing on this page is difficult. It is simply unfamiliar, and unfamiliarity is what makes a weak certificate look like a strong one.
What a diode array adds, and why the certificate never shows it
Non-chromophoric components — counter-ions, salts, some excipients — contribute mass to the vial and nothing at all to the chromatogram.
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.
From vial to bench: what is recorded and what is assumed
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 generic peptide method, and what it was designed for
A shallow gradient resolves impurities that a steep one runs into the parent peak. Both methods are legitimate; only one of them can see the small stuff.
A named analyst is the cheapest quality signal in this trade
Somebody has to be answerable for a release document. On most certificates in this market, nobody is named at all.
The chromatogram that appears on four documents
A PDF carries metadata about the software that produced it, and that metadata is frequently more informative than the content.
Chain of custody, and where it begins
Chain of custody, in a regulated setting, begins at sampling. Here it begins when the package arrives.
Accreditation, scope, and the question nobody asks VendorInvestigate
Two signatures — one who performed the work, one who approved its release — are the ordinary regulated convention and are almost unknown here.
An interlaboratory comparison nobody had run
The Journal submitted split samples from single lots to three assay services, under names unconnected to this publication, and published each method alongside each result.