Updated
The short answer
An independent analytical lab that runs reverse-phase HPLC for purity and mass spectrometry for identity can test a peptide for purity. Test strips, home kits and the seller's own paperwork cannot. Purity is a chromatography measurement, and it needs a lab instrument.
Which kinds of labs can do it
- Independent peptide testing labs. These labs work on peptides every day, so their columns, methods and reference handling are already set up for them. This is the best fit for most researchers and pharmacies.
- Large contract research organizations. They can run the work, but peptides are a small part of their business. Expect higher prices and longer queues.
- University analytical cores. They often have the instruments, but many only accept internal samples and do not issue a Certificate of Analysis in a format you can file.
Avoid relying on the seller's in-house lab. A report from the company that sold the product is not independent. See in-house vs third-party peptide testing.
What a purity test should include
- HPLC-UV purity (%). The main purity figure. The lab separates the sample on a reverse-phase column, reads it at 214 nm, and reports the main peak as a share of all peaks.
- Mass spec identity. Confirms the main peak is actually your peptide. A purity number without identity only tells you something is 98% pure, not what it is.
- Optional extras. Karl Fischer moisture, endotoxin (LAL), and heavy metals and residual solvents, depending on how the material will be used.
