The Purity Question

Part 1 — The Supply Chain

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.

Part 2 — Explainers

When a template becomes a misrepresentation

A blank certificate with the numbers left editable is an ordinary internal document. Its circulation as a finished record is the problem.

Part 3 — The Supply Chain

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.

Part 4 — Explainers

Twelve minutes or forty: what gradient slope buys

We set out the parameters a method disclosure would contain, all of which are known to whoever ran the sample and none of which is commercially sensitive.

Part 5 — Analytics

The certificate of analysis, line by line

The purity figure is the least informative line on a well-constructed certificate and the only line most buyers read.

Part 6 — The Supply Chain

Check the vial, not the box

The interval between manufacture and analysis is the most under-read figure on the page, and the one most likely to matter by the time a vial is opened.

Part 7 — Explainers

One measurement, twenty companies, forty compounds

A market that competes on one measurement will optimise that measurement. There are legitimate ways to raise a purity figure that involve no change to the product at all.

Part 8 — Analytics

The conservative convention: report the lower of two numbers

An orthogonal method separates on a different physical principle, so that species co-eluting in the first are likely to resolve in the second. Two runs of the same method at…

Part 9 — The Ledger

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.

Part 10 — Analytics

Where the solvent front ends is a decision, not a fact

The denominator excludes solvent-front features and injection artefacts by convention. Conventions differ on where the front ends, and a fragment eluting early exists in one…

Part 11 — The Supply Chain

Date of analysis, date of manufacture, and the gap between them

What happens to traceability when bulk material is subdivided, repackaged and relabelled two or three times before sale.

Part 12 — The Supply Chain

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.

Part 13 — Analytics

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.

Part 14 — Explainers

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.

Part 15 — Analytics

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…

Part 16 — Analytics

What the nitrogen said

Peptide content is the number that tells you how much drug is in the vial. Almost nobody sells it, almost nobody buys it, and when we paid for it on nine vials the results were…