Quality

How to evaluate a research peptide supplier

A twenty-five point rubric you can apply to any supplier in this market, including us. It scores documentation and claims discipline, because those are the only things a buyer can actually verify before purchase.

How to use this

Score one point per criterion met, working only from what a supplier publishes — no need to contact them. Five sections of five points. We have written it to be applied against us as readily as against anyone else, because a rubric only its author passes is a sales page. Where we currently fall short, we have said so at the bottom.

Section A · 5 points

Documentation

Whether evidence exists and can be found without asking.

	Criterion	Why
01	Certificates are published, not promised	Visible on the site, not “available on request” — which usually means not routinely produced.
02	Certificates carry a lot number	And it can be matched against the vial you receive.
03	Every lot is published, including sold-out lots	A durable record can be audited over time. A single rotating certificate cannot.
04	The chromatogram is shown, not just the percentage	The trace shows the impurity profile a number hides.
05	The testing laboratory is named	An unattributed result is a manufacturer claim in the format of a certificate.

Section B · 5 points

Analytical completeness

Whether the data answers the questions that matter.

	Criterion	Why
06	Net peptide content is reported	The most commonly omitted figure, and the one that determines how much peptide you actually have.
07	The content determination method is named	AAA, qNMR or elemental nitrogen — distinguishing a measurement from a calculation.
08	Counterion identity and percentage are stated	Without it the mass balance cannot be closed and content figures cannot be compared between suppliers.
09	HPLC conditions are stated	Gradient, run time and detection wavelength. Purity is method-dependent; a bare percentage is uninterpretable.
10	MS reports an observed mass and charge state	“Confirmed by MS” with no value is an assertion rather than a measurement.

Section C · 5 points

Claims discipline

Whether marketing language is bounded by evidence. This section is the most diagnostic, because it is where the gap between what a supplier knows and what it says becomes visible.

	Criterion	Why
11	No sterility claim without a sterility test	HPLC and MS cannot establish sterility. A vial described as sterile on the strength of chemical purity data is describing a test that was not run.
12	No endotoxin claim without an LAL result	Separate test, separate chapter, separate question from sterility.
13	Specifications and results are distinguishable	“≥99%” is what was ordered. “99.2%” is what was found. Presenting the first as the second is the commonest soft misrepresentation in this market.
14	Untested material is labelled as untested	Rather than left silent, or covered by a general claim about the catalogue.
15	Site-wide claims match product-level evidence	A banner asserting something the certificates do not support is the single clearest signal available.

Section D · 5 points

Technical credibility

Whether the supplier demonstrably understands the chemistry it sells.

	Criterion	Why
16	Educational content is factually correct	Check a compound's stated composition against its published sequence. Errors here indicate content produced without review.
17	References are primary	PubMed identifiers, DOIs and named journals — not links to other vendors.
18	Limitations are stated alongside capabilities	A supplier explaining what its testing cannot establish is describing a real quality system.
19	Storage guidance has a stated basis	Real-time or accelerated stability data, rather than a conventional figure.
20	Authorship is real and attributable	Named authors with verifiable credentials. Invented “Dr.” personas are common and are disqualifying.

Section E · 5 points

Operational transparency

Whether there is an accountable business behind the storefront.

	Criterion	Why
21	A real business identity is published	Registered name, jurisdiction, working contact route.
22	Terms, returns and shipping policies exist and are specific	Generic template policies indicate a storefront rather than an operation.
23	The stated use is consistent across the whole site	Including product pages, FAQ and any social channels. Inconsistency here is the pattern regulators cite.
24	Technical questions get technical answers	Ask which gradient produced a purity figure. The quality of the answer is highly diagnostic.
25	Corrections are made visibly	Dated updates and acknowledged errors indicate a maintained site rather than an abandoned one.

Interpretation

Reading the score

Score	What it indicates
20–25	Unusual in this market. Documentation is complete and claims are bounded by evidence.
14–19	Serious operation with gaps. Identify which section lost points — section C matters more than the others.
8–13	Typical of the market. Certificates exist but are incomplete, and marketing outruns evidence in places.
Below 8	You are relying on the supplier's word. That may be fine for exploratory work and is not fine for anything quantitative.

Applied to us

Where we currently stand

Publishing a rubric that scores us honestly is more useful to you than one calibrated to flatter us. Where we fall short, we would rather name it than obscure it.

Section A — documentation

Our certificate library is built lot by lot as testing completes, and every certificate stays published after its lot sells out. Until a compound's first lot is tested, its page says testing is pending rather than displaying a certificate from an earlier or unrelated batch. The library is at /testing.

Section B — analytical completeness

Our certificates report HPLC purity, mass spectrometry identity and net peptide content — criterion 06, and the field most often missing across this market. They carry the chromatogram and name the laboratory. We do not currently report counterion percentage or full HPLC gradient conditions, so we do not claim criteria 08 and 09.

Section C — claims discipline

We make no sterility or endotoxin claims, because we run neither test. Stating what has not been established is part of what we think a certificate is for — the reasoning is set out in what a certificate of analysis does not establish.

A rubric only its author passes is a sales page.

Common questions

Isn't a supplier publishing its own evaluation rubric a conflict of interest?

Yes, unavoidably — which is why the criteria are written as verifiable checks against published material rather than as judgements. Every one can be scored by a third party without contacting anyone. If a criterion looks tailored to advantage us, it is a bad criterion and worth discarding; the rubric is more useful to you than to us only if it survives that scrutiny.

Which single criterion is most predictive?

Number 15 — whether site-wide claims match product-level evidence. It requires no chemistry to check: read the homepage claims, then read a certificate, and see whether they agree. Where they diverge, the divergence tends to be systematic rather than accidental.

What if a supplier scores well but I have never heard of them?

Obscurity is not a quality signal in either direction. This rubric deliberately scores only what can be verified from published material, because reputation in this market is heavily influenced by marketing spend and affiliate arrangements. A new supplier with complete documentation is a better-evidenced proposition than an established one without it.

What this page is

A purchasing reference for laboratory research contexts. It is not medical advice, not a usage guide, and describes no application in humans or animals. Everything Ethereal Peptides supplies is a laboratory research material and is not for human or veterinary use.