← Knowledge · Updated 6 November 2026 · 5 min read
Repeatable results need repeatable material. Simple supplier qualification saves troubleshooting time later.
Ask for evidence
- A sample CoA, including chromatogram and mass spectrum
- The name of the testing lab and, where available, its accreditation
- A safety data sheet
- Details of counterion and peptide content
Check traceability
Each delivery should trace back to its CoA through the lot number. Ask how deviations and recalls are communicated.
Grading suppliers by risk
Not every material needs the same depth of checking. Grading by risk keeps the effort reasonable:
| Grade | Typical material | Requirements |
|---|---|---|
| Critical | Peptides for core series of experiments or reference measurements | CoA per lot with MS and HPLC, own incoming check, comparison of new lots |
| Standard | Peptides for pilot work and screening | CoA per lot, lot number check |
| Non-critical | Consumables such as swabs or syringes | Expiry date, undamaged packaging |
Questions for the supplier
Before a first larger order, a short list of questions pays off:
- Where and by whom is the peptide synthesised, and where is it tested?
- Is there a quality management system, for example to ISO 9001?
- Which tests come with the CoA as standard, and which are available on request?
- How is stock stored before dispatch?
- How are changes to synthesis, purification or testing lab communicated?
- How long does handling a complaint take?
The answers don’t have to be perfect. What matters is that they are specific and checkable.
Checklist before the first order
| Question | Good answer |
|---|---|
| Is there a CoA for each lot? | Yes, with lot number, date and testing lab |
| How was identity checked? | Mass spectrometry or LC-MS, with the measured mass |
| How was purity measured? | RP-HPLC, with the chromatogram attached |
| Is the peptide content stated? | Yes, or available on request |
| Can a lot be checked? | The number on the vial leads to the document |
| Are prices and contact details public? | Prices without logging in, an imprint and a working email |
Warning signs
- The same certificate for several lots or products
- Purity figures with no method, lab or chromatogram
- No imprint or no working contact address
- Claims of effects in humans for products sold for laboratory research
Assessing the first delivery
The first delivery is the best test of a new supplier. Check more than just the material:
- Did the parcel arrive in the time stated and undamaged?
- Do all vials carry a readable lot number and an expiry date?
- Are the CoA and safety data sheet there, and do they match the lot number?
- Do product, amount and form match the order?
- Did the supplier answer queries promptly and factually?
Record the result in a short note. At the next order you can then compare whether quality holds.
Comparing suppliers
If several suppliers are in the running, a simple score from 1 to 3 per criterion helps:
| Criterion | Weight |
|---|---|
| Completeness and quality of documents | High |
| Traceability through the lot number | High |
| Result of your own incoming check | High |
| Delivery time and packaging | Medium |
| Responsiveness and quality of answers | Medium |
| Price per mg | Medium |
Price is deliberately not first. A cheap peptide whose lot can’t be documented often costs more in the end, because experiments have to be repeated.
Do your own incoming check
For critical work, your own sample check is worthwhile, for example by LC-MS. Also compare lots in the same assay before moving a new lot into a running series.
Comparing new lots against old
If the lot changes in the middle of a series, a difference in results can come from the material rather than the experiment. So test the new lot alongside the old one in the same assay, at the same concentrations and on the same day. If the results fall within your usual spread, the new lot can be adopted. Keep a small retained sample of every lot for this.
Deviations and complaints
- Block the affected lot and label it clearly.
- Document the deviation with photos, lot number and measured values.
- Inform the supplier with the order number and ask for a response.
- Check whether experiments have already run with the lot and whether their results may be affected.
- Decide only after clarification whether the lot is released, returned or disposed of.
Ongoing review
Qualification is not a one-off. Review suppliers regularly, for example once a year, against a few simple criteria: delivery time met, documents complete, deviations occurred, response time to queries. For critical peptides a qualified second supplier can make sense. Then check that both sources give equivalent results in the assay.
Keep records
Record the supplier, lot, date received, storage location and use in the lab notebook.
| Entry | Example |
|---|---|
| Product and sequence | Name, sequence, salt form per CoA |
| Supplier and order number | Shop name, order number, order date |
| Lot and expiry date | As stated on vial and CoA |
| Receipt and storage location | Date, unit, shelf |
| Use | Experiment, date, amount used |
File the CoA and safety data sheet with this entry. That way every experiment can be matched to the material used, even years later.
How to check a shop’s claims day to day is covered in Buying peptides: how to identify a reputable supplier. How Alpenpeptid records and releases lots is under Lots.
Common questions
Does a small lab need formal supplier qualification? A lean version is usually enough: the checklist above, a filed sample CoA and a short note on the first delivery. What matters is that you can later trace which material was used.
Does the supplier have to use an accredited lab? Not necessarily, but accreditation to ISO/IEC 17025 makes the test results much more meaningful. Either way, ask which lab carries out the tests.
How much retained material should I keep? Enough for one comparison experiment and, if needed, an external analysis. For peptides that is often one unopened vial per lot.
For laboratory research use only. Not for use in humans or animals.
