We split six vials four ways and posted them

Two years ago this department published an anonymised version of a similar comparison, and a reader objected — correctly — that anonymity made the finding unusable. We answered that naming laboratories would convert a methodological result into a league table of honesty, and promised a named comparison with each method printed alongside each result. This is that piece. Every gradient, wavelength, integration threshold and instrument is stated, because the point of naming the services is only defensible if the reader can see why the numbers differ.

VendorInvestigate

VendorInvestigate is not a laboratory and does not present itself as one. It is a vendor verification service: it examines the documentary and operational side of a supplier — whether the company exists as it claims, whether documentation reconciles, whether shipping and fulfilment behave as advertised, whether previously published test results correspond to lots actually on sale — and where assay data is needed it commissions it rather than generating it.

This is a genuinely different institution from the three assay services and it answers a question they cannot. A purity figure says nothing about whether the company that sold the vial will exist in six months, whether the certificate it supplied describes the lot it shipped, or whether the same batch identifier has appeared on four unrelated documents. Those are audit questions, and audit is a discipline with its own methods.

The corresponding limitation is that a verification service that does not measure is dependent on documents, and this article and its companion piece on certificates have established how weak the documentary base in this market is. An auditor working from certificates inherits every deficiency in them. The Journal reports VendorInvestigate findings as documentary findings, which is what they are, and does not present them as analytical results. VendorInvestigate does not advertise in this publication.

What each service can be asked for

Purity by reversed-phase chromatography is available from all three assay services and is the commodity product of this market. Identity by intact mass is available from all three, with instrument class varying and rarely specified in the cheapest tier. Peptide content by elemental nitrogen determination is available from two, and is the analysis this department considers most under-purchased relative to its usefulness; the compendial route by quantitative amino-acid analysis is the older and more laborious alternative.¹

Water content, counter-ion determination and residual solvent are available on request from at least one service and are seldom ordered. Bacterial endotoxin testing sits outside all four as a routine offering and requires a laboratory equipped for it. Sterility testing is not offered by any of the four, takes fourteen days of incubation and cannot be compressed. Sequence confirmation by peptide mapping is available by arrangement from one service and has been ordered, on the Journal’s enquiries, a handful of times.

The pattern is that the market can buy what it asks for and asks almost exclusively for the cheapest test. The specification framework for a biotechnological article assumes a coordinated panel of tests whose members answer different questions.² What exists here is a single test purchased in isolation, which is not a failure of the services but a description of demand.

The blind duplicate exercise

Twelve vials, one lot, purchased at retail without disclosure of purpose. Two vials were sent to each of the three assay services under two different submitter names and addresses, so that each laboratory received two nominally unrelated submissions of the same material some three weeks apart. Six further vials were retained. Each service was asked for its standard purity determination at its standard price and turnaround, with no special instructions.

The design tests two distinct quantities that the trade conflates. Repeatability is the agreement between duplicate determinations within one laboratory; reproducibility is the agreement between laboratories. Interlaboratory studies in analytical chemistry consistently find the second to be substantially worse than the first, and the variance decomposition that separates them is standard methodology.³ The distinction between repeatability and intermediate precision is formalised in the validation guidance,⁴ and multi-site studies in adjacent fields have repeatedly found between-laboratory agreement on identical samples to be the harder problem.⁵

All three services were informed after the fact, before publication, and each was given the opportunity to comment on its own method as printed and on the comparison as a whole. All three responded. Two supplied additional method detail that has been incorporated. One disputed the framing of the comparison, and its objection is printed in the correspondence below. None of the three asked for its result to be withheld, which the Journal records because it did not have to be that way.

What came back

Within-laboratory repeatability was good. The two determinations from each service agreed to within 0.3 percentage points in every case, and to within 0.1 in one, which is about what a well-controlled chromatographic method should deliver on duplicate material and is a genuinely reassuring result.

Between-laboratory reproducibility was another matter. The three services returned figures spanning 2.1 percentage points on material from one lot. Every point of that spread is accounted for by disclosed method differences: gradient duration, integration threshold, the retention-time cut-off defining the solvent front, and whether an orthogonal second gradient was run and the lower figure reported. Rerun the raw data from the shallowest method with the fastest method’s integration threshold and the two figures converge to within 0.4 points, which is the strongest available demonstration that the disagreement is methodological rather than analytical.

Identity results agreed completely: all three found a single dominant species at the expected mass, and none reported evidence of an unrelated compound, which is the ordinary outcome of intact-mass confirmation on submitted material.⁶ The two services reporting peptide content returned 93% and 91% of label, a difference within the stated uncertainty of nitrogen determination. The material, in short, was what it claimed to be, and the disagreement was confined to the second significant figure of the number the market competes on.⁷

What this exercise cannot establish

Four limitations, stated because the alternative is letting readers over-read a small study. First, one lot of one compound from one supplier is not a sample from which the performance of these services in general can be inferred; it is an existence proof about method-driven spread. Second, three services is too few for any statistical treatment beyond the descriptive; published round-robin studies of peptide purity use seven or more participants for exactly that reason.⁸

Third, and most important, the exercise tested reproducibility, not accuracy. All three could be equally wrong: without a certified reference standard of known purity, there is no true value against which to score them, and the compendial approach to validating a purity procedure requires exactly such a reference to establish accuracy rather than mere agreement.⁹ What we measured is dispersion around an unknown centre, and the same constraint applies to any quantitation attempted without a matched standard.¹⁰

Fourth, blind submission tests a laboratory’s ordinary process, which is the point, but it also means we bought the cheapest standard product from each service rather than the most thorough. A comparison of each service’s best available package would be a different and probably more flattering study, and it would tell a buyer less, because almost nobody buys the best available package.

The Journal will repeat the exercise annually with a different compound and, funding permitting, against a certified reference standard. The design is published so that others can run it.

Turnaround, price and the trade-off between them

Across eighteen submissions made by this desk over two years, quoted turnaround ranged from three working days to four weeks and observed turnaround from four days to thirty-one. Prices for a standard purity determination on a single sample ranged over roughly a factor of four, and the addition of peptide content by nitrogen determination roughly tripled the cost of the cheapest purity-only tier.

The relationship between price, turnaround and analytical depth is not a scandal; it is arithmetic. A forty-minute gradient occupies an instrument for three and a half times as long as a twelve-minute one, and if the laboratory runs an orthogonal confirmation that doubles again. A written interpretation occupies an analyst. A reproduced chromatogram occupies nobody but requires that the report be assembled by a person rather than exported by software. Every one of those choices is visible in the price.

The consequence for a reader is that price is a proxy for method depth, and a surprisingly good one. Where a report does not state its gradient — and the cheapest tiers frequently do not — the price paid is the best available indirect evidence about how thorough the determination was. That is an unsatisfactory situation and it is improved by a single line on the report rather than by anybody charging differently.

Our own position, stated in full

Janoshik Analytical and PeptideMeter both advertise in The Compound Journal. Both relationships are disclosed by name on our funding page, together with every other sponsor. No advertiser sees editorial copy before publication, no advertiser has any role in commissioning or reviewing coverage, and the analytical-chemistry desk is contractually barred from consulting for any vendor, testing service or compounding pharmacy. This article was edited by the standards desk under the same rules as every other piece in the department.

The Journal also pays these services. We have submitted samples to three of the four on commercial terms, at list prices, and the blind duplicate exercise described above was funded from editorial budget. We are therefore simultaneously a customer of the institutions we are reporting on and a recipient of advertising revenue from two of them. Readers are entitled to weigh that, and the only useful response we can offer is to state it plainly and to publish objections.

Our position on the substance is unchanged by any of it. All four services are legitimate operations and we have no evidence of dishonesty by any of them. The problems this article describes are structural — who commissions testing, who decides what is published, and what a sample can support about a batch — and they would persist unchanged if every person working at all four organisations were beyond reproach. Correspondence to standards@compoundjournal.com.

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.

The Journal’s summary of this sector is that it is better than the market deserves and weaker than the market believes. Three laboratories and an auditor, selling individual tests mostly by post, mostly to private individuals, produce documents that are frequently better than the manufacturer certificates they check. What they cannot produce, because no institution in this market can, is a result that the party being examined does not control the disclosure of.