UK research labs evaluating a peptide supplier are looking at the same shortlist of criteria that procurement and EHS teams have always asked about — adapted for a market where many vendors are international, the regulatory boundary between RUO and pharmaceutical-grade is sharp, and post-2021 customs rules add a layer of paperwork. This checklist is the one we use internally and is the one we would expect any reputable supplier to be able to satisfy.
1. Documentation
A supplier should be able to produce, on request, before you place an order:
- A specimen lot-specific certificate of analysis showing RP-HPLC purity, ESI-MS identity, water content, counter-ion percentage and net peptide content. See how to read a peptide COA.
- A current safety data sheet for each line item.
- Their COA policy (per-lot or per-product?). See ours: COA policy.
If a supplier cannot produce a sample COA before the order is placed, treat the omission as disqualifying.
2. Quality control
What is on the COA, and what is not, matters as much as the headline purity number:
- Purity at 220 nm, not only 280 nm.
- Mass-spec confirmation (ESI-MS minimum; high-res preferred for novel sequences).
- Counter-ion identity and percentage (acetate vs TFA).
- Water content by Karl Fischer.
- Net peptide content — derive concentrations from this, not from label fill mass.
A supplier whose COA omits net peptide content is reporting an incomplete result. See What ≥99% HPLC purity actually means for the wider context.
3. Traceability
- Every vial labelled with lot number matching the COA.
- Lot numbers retained by the supplier for at least 2 years after lot exhaustion (regulatory standard).
- A documented procedure for handling a non-conformance or recall.
4. Dispatch and packaging
- Cold-chain shipping with temperature reserve appropriate to the route.
- Sealed primary packaging; tamper-evident outer.
- For UK consignees, full customs paperwork in the box: commercial invoice, packing list, COAs, SDSs. See UK dispatch, customs and research peptides.
5. Lead time
- Realistic dispatch SLA. We dispatch in-stock orders the same day if placed before 13:00 CET.
- Honest backorder communication. A supplier who marks out-of-stock items “in stock” loses procurement trust on the first slip.
6. Payment, terms and tax
- Recognised payment methods (card, bank transfer; cryptocurrency is acceptable where the lab’s institutional policy allows).
- Clear pricing in a single currency on the order confirmation.
- A VAT-compliant invoice on every order. UK consignees with an EORI and VAT number may be eligible for postponed VAT accounting.
- A documented refund and return policy.
7. Customer support
- A real technical contact who can answer compound-specific questions (reconstitution, storage, sequence-specific stability liabilities).
- Response within one working day on technical questions, same day on order-status questions.
8. Compliance posture
- A clearly published RUO statement on every product and at the point of sale. See What “for research use only” means.
- No marketing copy that crosses into therapeutic claims (a vendor pitching peptides for human consumption is a vendor outside the RUO scope and is not the right partner for a research lab).
- Visible address and corporate identity. A UK consignee should be able to find a registered company name on the supplier’s About page.
9. Red flags
| Signal | Why it matters |
|---|---|
| No COA available before order | The supplier is either selling a generic spec sheet or has nothing to show. Either disqualifies. |
| Headline purity quoted at 280 nm only | Aromatic-only detection underestimates the impurity profile for non-Trp/Tyr peptides. |
| Marketing claims of human or veterinary efficacy | Out of scope for an RUO supplier; raises liability concerns for the buyer. |
| No registered company address | Difficult to enforce a return; harder for procurement to onboard. |
| ”In stock” status that does not change for weeks | Inventory display likely not real-time; expect lead-time surprises. |
| Pricing that fluctuates between page load and checkout | A revenue management tactic that does not belong in a B2B research supply relationship. |
10. After the first order
- Confirm the COA accompanying the shipment matches the lot on the vials.
- Place the vials in
−20 °Cstorage promptly; equilibrate to room temperature before opening on first use. See storage & handling best practices. - Record the supplier’s response time and dispatch performance. Two or three orders is enough to characterise their reliability for procurement reviews.