The core tests on a peptide certificate
| Test | What it answers | Method |
|---|---|---|
| Identity | Is this the right molecule? | Mass spectrometry: the measured mass is compared with the mass expected from the sequence |
| Purity | How much of the peptide material is the right sequence? | Reversed-phase HPLC with UV detection, usually at 220 nm |
| Appearance | Does the material look as it should? | Visual inspection against the specification |
Tests reported for many batches
| Test | What it answers | Method |
|---|---|---|
| Net peptide content | How much of the powder's weight is peptide? | Elemental (nitrogen) analysis or amino acid analysis |
| Water content | How much moisture is in the powder? | Usually Karl Fischer titration |
| Counter-ion content | How much acetate or trifluoroacetate is bound to the peptide? | Ion chromatography or HPLC |
| Endotoxin | Is there bacterial endotoxin, and how much? | An endotoxin assay |
If a certificate doesn't show a result, that test wasn't done for that batch.
What we check ourselves
When a batch arrives with us, before it can be sold:
- Documents against product. The batch number and expiry on the labels must match the manufacturer's certificate and the shipping documents.
- Condition on arrival. Packaging intact, temperature indicators checked where the product travels cold.
- Storage. The batch goes straight to the storage condition on its label.
- Records. The batch is entered in our system so every later quotation, packing list and delivery note carries its number and expiry.
Our suppliers are manufacturers that have passed our supplier checks, and we keep their batch documentation for every lot we sell.
What testing can and can't tell you
Testing can confirm what a batch is and how pure it is. It doesn't tell you how the product has been stored since, which is why we ship at the labelled temperature and say so on the packing list (see storage and shipping). It doesn't make a research-grade product suitable for any use in people or animals; research-grade products are for laboratory research only. And a purity figure with no batch, method or laboratory attached is a claim, not a result: peptide purity and net peptide content explains why.
Testing a sample yourself
If you want to test a sample independently, analytical laboratories that test peptides can run HPLC purity and mass spectrometry identity, and many will add net peptide content or endotoxin. Ask for the method, the chromatogram and the mass spectrum with the report, and quote the batch number so the result can be matched to the certificate. Our guide to reading a certificate of analysis explains what to look for in the report.
If an independent result for one of our batches differs from the certificate, please send it to us at info@ukmasterpeptides.com. We will look into it.
Questions people ask
- Are your peptides third-party tested?
Every batch is tested by its manufacturer.
- What tests show a peptide is genuine?
Mass spectrometry for identity and HPLC for purity, reported for the specific batch by a named laboratory.
- Do you test for endotoxin?
Where the batch has been tested for endotoxin, the result is on its certificate.
- Can I get the chromatogram?
Ask us for the chromatogram and mass spectrum for any batch. If they aren't already on file, we request them from the manufacturer.