Chain of custody, and where it begins

The distinction between a sample and a batch is the one the trade most consistently collapses. A laboratory reporting 98.6% purity on a submitted vial has made a defensible statement about that vial. Whether the statement extends to the other four hundred vials filled from the same bulk depends on the homogeneity of the fill, on whether the vial was drawn at the beginning, middle or end of the run, and on whether it was stored with the rest. None of those facts is available to the laboratory, and a report that carefully says “the sample submitted” is routinely quoted as though it said “the batch”.

The sample is not the batch

The most important sentence in every third-party report in this market is the one identifying what was tested, and it always says the same thing: the sample submitted. That phrasing is precise and correct, and the entire trade reads past it. A result obtained on one vial extends to a batch only if the vial is representative, and representativeness is a property of how the vial was selected, not of how carefully it was analysed.

In regulated practice, sampling is a controlled activity in its own right: the accreditation standard treats it as part of the laboratory activity, requiring a documented sampling plan and records of how the portion tested was obtained.¹ Where a laboratory receives a sample it did not draw, the standard expects the report to make clear that the results apply to the sample as received. All four services do this. The market quotes them anyway as though the batch had been tested, which inverts the pharmacopoeial convention that a result on a sample is evidence about a batch only under a stated sampling assumption.²

The practical significance depends on the fill. A batch filled in a single session from a homogeneous bulk solution is likely to be uniform, and a single vial is decent evidence about it. A batch assembled from subdivided bulk, filled across sessions, or blended from more than one synthesis is not, and a single vial is evidence about a vial. Nothing on a report tells a reader which situation applies, because the laboratory does not know either.

Custody begins at the reception desk

What a laboratory can record about a submitted sample begins at the moment of receipt, and the better reports in this market record a surprising amount: the date and time of arrival, the condition of the outer packaging, whether cold-chain materials were present and still cold, whether the vial seal was intact, whether the crimp showed evidence of having been lifted, and the appearance of the cake. Two of the four services record most of this as standard. The others record some of it.

These lines are worth more than they look. A vial arriving with a collapsed cake or a discoloured plug is telling a reader about storage and transit history that no purity figure captures, and a report that notes it has converted an unknown into a datum. Condition on arrival is also the only point in the entire chain at which anybody independent observes the material’s physical state, and it is therefore the only opportunity to catch a transit problem before it is analysed away.

What no laboratory can record is what happened before the package was posted. The submitter’s storage, the route from vendor to submitter, the number of times the vial changed hands, the ambient temperature of a fortnight in a sorting facility: all of it is prior to custody and none of it is knowable. The Journal accordingly cites third-party purity figures with the submission date and, where we know it, the submitter, because those two facts bound what the figure can support.

Who chose the vial

The identity of the submitter is the single most informative piece of context attached to any third-party report, and it is the piece most often missing when a report is quoted. A test commissioned by a buyer on a vial bought anonymously at retail is a different evidential object from a test commissioned by the vendor on a vial it selected from its own stock. Both are legitimate. They support different inferences, and the difference is not small.

In the buyer-submitted case the vial entered the postal system as an ordinary retail unit and its selection was outside the vendor’s control, which is exactly the property that makes the result informative about what a customer receives. In the vendor-submitted case the vendor chose the vial, knew it was being tested, and will decide whether the result is published. Nothing improper need occur for the second to produce a more flattering picture than the first, and no laboratory can distinguish them from the bench.

The Journal’s practice is to state the submitter type wherever it cites a figure, and to decline to cite a figure where the submitter is unknown. This is more restrictive than the market’s convention and it means we publish fewer numbers. It also means that when we say a result came from an anonymous retail purchase, that claim is doing work.

How a claim decays between the bench and the listing

The decay is worth tracing precisely, because at no step does anybody say anything false. The laboratory reports a purity figure for the sample as received, on a stated date, by a stated method, submitted by a named party. The vendor extracts the figure and the service name onto its own documentation, dropping the submitter and often the method. A reseller reproduces the vendor’s documentation, dropping the date. A listing summarises the whole chain as tested by a named service. A badge reduces it to verified.

Each step is a reasonable act of summarisation and the cumulative effect is a claim of a different kind from the one the laboratory made. A time-indexed measurement on one sample has become an atemporal property of a product line. The information was not concealed; it was compressed away by a chain of parties each of whom had a legitimate reason to shorten the message.

This is why the Journal reports the provenance of every third-party figure it cites — which service, which lot, which date, which submitter — and treats a figure lacking any of those as uncitable. It makes our coverage sparser than the market’s. It also means that a number appearing in this publication can be traced to a document, which is the only property that distinguishes reporting from repetition.

What the Journal thinks these services are worth

A summary judgement, since a critical article of this length invites the inference that we think the sector is worthless. We do not. Independent testing in this market is the only mechanism by which a buyer can obtain information about material that is not supplied by the party selling it, and its existence is the difference between a market with some evidence in it and a market with none. Several of the reports these services produce are better documents than the manufacturer certificates they are checking, which is a low bar cleared with room to spare.

The three criticisms we would press are narrow. A sample is not a batch, and the trade cites samples as batches. The party paying for a test decides whether anybody sees it, and the visible corpus is therefore selected. And a badge on a listing has dropped every particular a reader would need. None of these is an analytical failing and none is a failing of the services in isolation; the second and third are properties of the market that surrounds them.

What we would tell a reader is this. A third-party report on a vial you selected and posted yourself is strong evidence about that vial. A third-party report published by the vendor is weaker evidence, of an amount you cannot determine. A badge is not evidence. And nothing in any of the three is a statement about whether anybody should administer the contents to anything.

One thing this article has deliberately not done is rank the four services. We do not think the evidence supports a ranking, we do not think a ranking would be used carefully, and two of the four advertise here, which is a reason for additional caution rather than a reason to pretend the relationship does not exist. What we have tried to publish instead is the material a reader would need to rank them for their own purposes.