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.
TheCompound Journal
Reporting on incretins, compounding & the peptide supply chain
Verification
Every step between the laboratory report and the product page removes information, and the badge is the last step.
The Journal’s position is that a verification badge, in the form it currently takes across this market, is not evidence. It is a claim that evidence exists somewhere, and it withholds every particular a reader would need to assess it. This is not a criticism of the laboratories, which do not design vendors’ product pages, and it is not usually a criticism of the vendors either, since the convention long predates any of them and buyers demonstrably respond to the graphic.
A frequently overlooked asymmetry: none of these services has any authority over a vendor. A laboratory that finds a submitted sample at 91% purity cannot compel a recall, cannot require a retest, cannot publish the finding over the client’s objection without breaching confidentiality, and cannot prevent the vendor from continuing to advertise a figure obtained on a different lot. It can decline further business, which is a real sanction and a slow one.
This is not a shortcoming of the services. Confidentiality to the client is a requirement of the accreditation framework, not an indulgence, and a laboratory that published clients’ results unilaterally would be a worse institution, not a better one. But it means the word verification is doing something the underlying arrangement cannot support: verification in ordinary usage implies a check that can fail with consequences, and here the only consequence of a bad result is that nobody hears about it.
The one structural exception is the public archive. Where a service records that a submission occurred, a vendor cannot quietly discard an unfavourable result, because the fact of the test is on the record even if the detail is not. That is why this article treats the archive as the most important product feature in the sector, and why the Journal’s standing request to all four services is that the existence of a submission be public even where the result is confidential.
Across the four services the Journal has catalogued eleven elements that appear on some reports and not others: the compound and lot as declared by the submitter; the date of receipt; the condition of the sample on arrival; the instrument; the column; the gradient; the detection wavelength; the integration threshold; the reproduced chromatogram; a named analyst; and an explicit statement that results apply to the sample as received.
No service omits all of these and none includes all of them on every tier. The best reports in the sector carry nine or ten and are genuinely good documents by any standard — better, in several respects, than the manufacturer certificates they are checking. The thinnest carry three, and a three-element report is a number with a letterhead.
The reporting requirements in the accreditation standard are the natural benchmark here, and they are not demanding: identification of the items tested, the date of receipt, the methods used, the results with units, and a clear statement of what the results apply to.1 A report meeting that list is checkable. The Journal’s standing request to all four services is a single addition beyond it — print the gradient and the integration threshold — because those two numbers are what make a purity figure comparable with anybody else’s.
A badge is not evidence. It is an assertion that evidence exists, offered without the particulars that would let anybody assess it.
The Journal’s standing positionA verification badge on a product listing typically asserts, in one or two words and a graphic, that the product has been tested by a named service. Consider what that claim leaves open. Which lot was tested. When. Who submitted the sample and how it was selected. What was measured — purity alone, or identity, or content. By what method. Whether the lot currently on sale is the lot that was tested. Whether the report is available to the reader.
Every one of those is material and every one is absent. A badge is therefore not evidence; it is an assertion that evidence exists, offered without the particulars that would let anybody assess it. The Journal does not treat badges as evidence in its coverage, states so wherever it reports one, and will not cite a badge as support for a claim about material.
The remedy is four data points the vendor already possesses: the lot number, the date of analysis, the service, and a link to the report. Several listings in this market already carry them, which establishes both that it is possible and that it is not commercially fatal. What it requires is that a badge become perishable — attached to a lot rather than to a product line — and perishability is precisely the property a marketing asset is designed not to have.
| Question a reader has | On a typical badge | On a lot-linked badge |
|---|---|---|
| Which service tested it? | Usually stated | Stated |
| Which lot was tested? | Absent | Stated |
| On what date? | Absent | Stated |
| Who submitted the sample? | Absent | Stated |
| What was measured? | Absent | Stated |
| By what method? | Absent | In the linked report |
| Is the report readable? | Absent | Linked |
| Does it apply to the lot on sale? | Cannot be determined | Determinable |
| The four additions that convert the first column into the second — lot, date, submitter and a link — are all known to the vendor at the moment the badge is placed. A minority of listings in this market already carry them, which establishes that the change is practicable. | ||
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.
First, publication of submissions rather than only of results: the date, the vendor as named by the submitter, and the compound, with the result confidential where the client requires it. This defeats most of the selection effect and costs nothing.
Second, submitter type on every report — vendor, buyer, publication or reseller — which the laboratory knows and which determines what the result can support. Third, lot-linked badges carrying a lot number, a date and a link, so that a verification claim expires with the lot it describes. Fourth, gradient and integration threshold printed on every purity report, which is the only way two figures from different services can be compared at all.
None of the four requires a regulator, new legislation, or any change in analytical practice. Three of them require a laboratory to print information it already holds; the fourth requires a vendor to accept that a badge should perish. The Journal has put all four to each of the services covered here. Responses have been mixed and mostly constructive, and are printed in our correspondence pages as they arrive. We will publish an annual note on which have been adopted, because the alternative is making the same request indefinitely without recording the answer.
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.
Selected from correspondence received on this article. Writers are identified by initial, surname and city, verified before printing. Replies are from the desk that filed the piece or from the standards editor. Write to letters@compoundjournal.com.
As a buyer I found the section on who chose the vial genuinely clarifying and slightly deflating. I have been treating vendor-published reports as equivalent to my own submissions for two years, and on your account they are not equivalent by an amount that cannot be measured.
— K. Mwangi, Nakuru
That is the correct reading, and the unmeasurable part is the honest part. We would add only that vendor-published reports are not worthless — a vendor willing to commission testing at all is behaving better than one that will not — they are simply weaker in a specific way.
Your selection-effect model assumes a supplier publishes results above a fixed threshold. Real behaviour is surely more complicated: a supplier might publish a poor result on a batch it has withdrawn, or publish everything for a period to establish credibility and then stop. The arithmetic is fine and the behavioural assumption is a cartoon.
— D. Ó Súilleabháin, Killarney
Agreed, and the figure caption now says illustrative arithmetic rather than model. The point survives the simplification, which is that a small amount of selection produces a large apparent effect, but we should not have dressed a demonstration as an estimate.
Your suggestion that laboratories publish the fact of a submission while keeping the result confidential is the first proposal I have read in this area that a laboratory could actually implement without breaching a client obligation. I have raised it internally.
— S. Ó Ceallaigh, Limerick
We would be glad to report the outcome either way, including if the answer is no and the reason is commercial. The proposal is only useful if somebody adopts it, and a published refusal is more informative than silence.
You disclose that two of these services advertise with you and then spend four thousand words on structural criticism of the sector they operate in. I cannot decide whether that is admirable independence or an elaborate way of appearing independent. Probably the former. I wanted to say that I noticed the question.
— R. Cadogan, Bridgetown
So do we, every time this department writes about the sector. The only answers we have are procedural: the disclosure, the standards desk edit, the consulting prohibition on the writer, and the practice of printing objections like yours unedited.
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 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.
Reported from the analysis, not from a warning notice.
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…
Reported from the analysis, not from a warning notice.
Reported from the analysis, not from a warning notice.