Criteria for choosing a research-peptide supplier: what to check and how

A research-peptide supplier is judged by what it can prove, not by what it states. Five criteria carry real meaning — per-batch documentation, traceability, transparency about provenance, an identifiable business that actually communicates, and written return terms — and each one translates into a check with a yes-or-no answer that can, most of the time, be verified outside the seller's own website. Price, page design and reviews are not on the list; they say something about the commercial experience, not about the material.

This is a list of criteria, not a ranking. It names no suppliers and recommends none. The specific questions to send before a first order, the check of the online shop as a business, and the comparison between a domestic and a foreign supplier are covered separately in the companion articles of this series. A checklist is only worth something if anyone can fail it — and this one applies to every supplier, including the one that publishes it.

Why criteria rather than a list of names

In regulated settings, suppliers are not chosen on reputation. ISO 9001:2015 requires an organisation to determine and apply criteria for the evaluation, selection, monitoring of performance and re-evaluation of external providers, and to retain documented information on the results ^[1]. The ICH Q7 guide for active pharmaceutical ingredients is more specific still: materials are purchased against an agreed specification, from suppliers approved by the quality unit ^[2]. A small laboratory does not need a certified quality system to borrow the logic: the criteria are written before the order, applied the same way to every candidate, and the answer is recorded.

There is a second reason. A list of names goes stale within months — suppliers change sources, laboratories, even owners — whereas a criterion does not. A supplier that passed every check last year may fail this year, and that only shows if the check is repeated. That is why the standard speaks of re-evaluation rather than one-off approval ^[1].

Documentation: what the supplier must be able to produce

The first criterion is also the easiest to check. For every batch it sells, the supplier should be able to provide a certificate of analysis carrying the batch number, the name and address of the laboratory that performed the tests, a report number, dates, and for each test the method, the acceptance criterion and the result. That is the common ground between the World Health Organization's model certificate and ICH Q7 ^[2][3]; anyone who wants the meaning of each line in turn will find a field-by-field guide to reading a certificate of analysis. In practice, the supplier should be able to produce:

• A certificate of analysis for the specific batch, not a "typical" or "representative" document per product code.
• The full chromatogram with method parameters when asked, not only the summary page.
• Identity confirmation by mass spectrometry, beyond a purity percentage.
• A safety data sheet for the substance, where chemicals legislation requires one.
• The laboratory's details in a form that lets you contact it directly, without the seller in between.

An accreditation claim is particularly easy to check. Accreditation to ISO/IEC 17025 applies to the laboratory, not the product, and is granted per method and per scope ^[4]; for Greek laboratories, the Hellenic Accreditation System publishes a catalogue searchable by name and certificate number ^[5]. The question to put to a supplier is not "do you work with an accredited laboratory?" but "what is the certificate number, and does its scope include the method printed on the COA?"

Batch traceability

A flawless certificate is worth nothing if it is not tied to the vial you will receive. The tie is a single number: the batch number, which should appear verbatim on the label, on the certificate and, ideally, on the delivery note or invoice. ICH Q7 describes the same requirement for distributors, traders and repackers: they must maintain complete traceability of the material they handle, with the identity and address of the original manufacturer, purchase orders, transport and receipt documents, the manufacturer's batch number and all authentic certificates of analysis ^[2].

From the buyer's side, the criterion is simple to state: given a batch number, can the supplier say when it received the batch, from whom, with which certificate, and whether any vials have been opened, repacked or relabelled? If the answer arrives within a working day, a system exists. If it never arrives, none does. The matching record on your own side — what you keep at receipt so the batch stays bound to the material — is described in the minimum record set for batch traceability.

Transparency about provenance

Most research-peptide suppliers do not synthesise anything themselves. They buy from a manufacturer, often through an intermediary, and sell the material under their own label. That is not a problem; it is how the trade works. The problem arises when the buyer cannot find out which link in the chain issued the certificate being shown. ICH Q7 requires that, where the supplier of a critical material is not its manufacturer, the manufacturer's name and address be known; and where a certificate is reissued by an intermediary, the laboratory that performed the analysis must be named and the original attached ^[2].

Transparency, then, does not mean the supplier disclosing its commercial relationships. It means answering three things: whether the certificate is the manufacturer's, the supplier's own, or an independent laboratory's; whether the analysis was done before or after repacking; and in which country synthesis took place. The same phrase, "lab tested", can cover any of the three cases, and the difference between them is explained in what the phrase "lab tested" means in practice.

Communication and technical support

The fourth criterion has a legal basis. The Directive on electronic commerce requires every provider to make its name, the geographic address at which it is established, contact details allowing rapid and direct communication including an email address, the trade register and registration number, and its VAT number easily, directly and permanently accessible ^[7]. A supplier that cannot be identified as a business cannot be assessed as a supplier — the check stops there.

Beyond identity, the quality of the answers counts. Send one technical question in writing — about the salt form, the analytical method, storage conditions before dispatch — and note whether the reply is specific, whether it comes from someone who understood the question, and whether it is given in writing. There is also an inverse criterion that is just as useful: a supplier of research material does not give instructions for administration to people. If "support" offers to explain amounts, frequencies or the expected effect on the body, the supplier has already said something important about how it understands its own product.

Return terms and what they reveal

In distance sales to consumers, Directive 2011/83/EU grants a fourteen-day withdrawal period, with exceptions — among them sealed goods that are not suitable for return for health-protection or hygiene reasons once unsealed after delivery, and goods liable to deteriorate rapidly ^[6]. The same Directive requires the trader to inform the consumer before the contract is concluded of the conditions, time limit and procedure for exercising the right, or of the fact that it does not apply ^[6].

That is why return terms are an assessment criterion rather than a commercial detail. A serious supplier states plainly what can and cannot be returned, explains why a vial that has left controlled storage is not resold, and separates change of mind from defective or wrong material, for which it describes a procedure: photographs, batch number, a deadline for reporting. Terms promising "no-questions-asked refunds" on cold-chain material are as worrying as terms that do not exist at all: they mean either that nobody ever read them or that returned material goes back into stock.

A practical checklist

The table sets the criteria out in a form that can be filled in. Each row is answered "yes", "no" or "not answered", and the third option is recorded separately: it is not the same as "no", but it is certainly not "yes".

Fill the table in once before the first order and again whenever something changes — a new laboratory, a new address, a new certificate format. Keep it with the documents that support it. A checklist without the messages and files behind each answer is an opinion, not a record.

What these criteria do not judge

None of the above proves what a vial contains. The criteria test whether a supplier works in a way that leaves traces — documents, numbers, answers — that a third party can confirm. That sharply limits carelessness but does not rule out intent: a genuine certificate can accompany the wrong material, and a correct batch can degrade in transit. Where the outcome of an experiment depends on the identity and purity of the material, the only conclusive evidence is analysis of a sample by an independent laboratory.

Price, the look of the website and customer reviews also stay off the list. Price says something about the market, not about the batch. Appearance costs little and is easily copied. Reviews, even genuine ones, describe service and delivery — rarely anything the writer could actually measure. That is useful information, but it answers a different question.