Ten questions to ask a peptide supplier before ordering

Five minutes of questions before a first order tells you more about a research peptide supplier than any amount of reading their website, because the website was written to be read and the answers were not. This note gives the questions worth asking, what a good answer sounds like, what a poor one sounds like, and Alphex's own answers, so you can hold us to the same test. All Alphex products are for laboratory and in-vitro research only.

Ten questions

1. "Can you send me the Certificate of Analysis for the batch of [compound] you have in stock right now?"
   Good: a specific PDF within the hour, with batch number, chromatogram, mass spectrum, laboratory name and date. Poor: a generic document, "it comes with the order", or silence.
   Alphex: yes, via the COA request form; the certificate is for the batch in the freezer.
2. "Which laboratory tested it, and can I contact them?"
   Good: a named independent laboratory and no objection. Poor: "our lab", a redacted name, or a refusal.
   Alphex: named on every certificate; we will make the introduction. See verifying a COA with the lab.
3. "Is the purity measured at 220 nm, and against a reference standard?"
   Good: yes and yes, with the method on the certificate. Poor: doesn't know.
   Alphex: 220 nm, reference standard, 99+% threshold. See how HPLC purity is calculated.
4. "Where is the stock physically held, and where will my parcel ship from?"
   Good: a UK location and a UK courier origin. Poor: evasion. See why UK stock matters.
   Alphex: UK stock, UK courier, same-day dispatch before 2pm Monday to Friday.
5. "What salt form is it?"
   Good: acetate or TFA stated. Poor: doesn't know. See acetate versus TFA.
   Alphex: acetate; GHK-Cu as the copper complex.
6. "Does the label mass mean gross solid or net peptide?"
   Good: gross, honestly stated. Poor: claims 100% net.
   Alphex: gross. See net peptide content.
7. "What happens if my own testing finds the batch below the stated purity?"
   Good: replacement or refund against the batch number, with a stated process. Poor: no policy.
   Alphex: replace or refund. See the purity guarantee.
8. "Do you sell for research use only, and what do you do about orders that aren't?"
   Good: yes, confirmation at checkout, orders declined. Poor: no restriction, or marketing that says otherwise.
   Alphex: yes; see research use only.
9. "Do you test every batch, or the product line?"
   Good: every batch, new certificate each time. Poor: one certificate ever.
   Alphex: every batch. See batch matching.
10. "Who are you?" Company name, registration number, address, a person to talk to.
    Alphex: Alphex Limited, Companies House 16674899, lewis@alphex.co.uk.

How to read the answers

Speed and specificity matter as much as content. A supplier who can answer all ten in one email has the material, the documents and the process in front of them. One who needs to "check with the warehouse" for the batch number is telling you they do not hold it. One who is irritated by question two has something to be irritated about. See supplier red flags and the positive framing in the 12-point supplier checklist.

Alphex research peptides are supplied for laboratory and in-vitro research by qualified researchers only. They are not authorised for human or veterinary use.

Research use only. Alphex products are supplied exclusively for laboratory and in-vitro research by qualified researchers. They are not authorised for human or veterinary use, and nothing in this note is advice on any such use.

Published 17 March 2026. Alphex reviews research notes when the testing method, the catalogue or UK guidance changes.

Alphex Research Team

Alphex Limited, UK research peptide supplier

The Alphex research team writes and maintains these notes for UK laboratories buying research peptides. Every batch Alphex lists is verified by reverse-phase HPLC with a batch-matched Certificate of Analysis. Content covers laboratory and in-vitro research only.