Custody, condition and the temperature nobody logged
What a laboratory can and cannot know about the provenance, storage history and representativeness of what lands on its bench.
Janoshik Analytical
Page 7 of 7 of this archive, newest first.
The submitted sample: the weakest link in the whole system
The condition on arrival is recorded by some services and not others, and it is one of the more informative lines in a report.
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.
Two analysts, one chromatogram, two answers
We work through a single chromatogram twice, under two integration conventions, and show where the difference comes from.
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.
A tested vial is evidence about a vial
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.
Six words a verification badge would need to mean anything
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.
Blind duplicates: what happens when a laboratory does not know it is being watched
Duplicate submissions under different names test within-laboratory repeatability, which is a different quantity from between-laboratory reproducibility.
The number at the bottom of the certificate
A purity percentage is the most quoted figure in the research-peptide trade and one of the least examined. We asked four laboratories to analyse the same vial and got four…
Equal area is not equal mass: the response factor problem
Peptide bonds absorb strongly near 214 nm; aromatic side chains absorb near 280 nm. A method reading at 280 is blind to any fragment lacking an aromatic residue.
A tested vial is evidence about a vial
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.
Blind duplicates: what happens when a laboratory does not know it is being watched
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.
Why two wavelengths on one run would settle several arguments
Non-chromophoric components — counter-ions, salts, some excipients — contribute mass to the vial and nothing at all to the chromatogram.
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.
A tested vial is evidence about a vial
The condition on arrival is recorded by some services and not others, and it is one of the more informative lines in a report.
Six words a verification badge would need to mean anything
Lot-level verification with a public report is a real and achievable thing. It exists in this market, on a minority of listings.
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.
How a claim degrades between the bench and the listing
The Journal does not treat a badge as evidence and states so wherever it reports one.
What orthogonal actually means, and what it does not
The most useful single addition to any purity determination is a second separation under a different pH or on a different stationary phase, and the second-most useful is a…
The submitted sample: the weakest link in the whole system
What a laboratory can and cannot know about the provenance, storage history and representativeness of what lands on its bench.