Which peptide tests do you actually need — identity, purity, net content, endotoxin, sterility?

Start with three measurements: purity (HPLC), identity (mass spectrometry) and net content. Together they catch the wrong molecule and the underfilled vial, which purity alone can't. The others answer different questions:

• Endotoxin (LAL, in EU/mg): bacterial residue that can cause fever and reactions when injected. Endotoxin Testing for Peptides
• Sterility (USP <71>): whether anything grows in the sample. Peptide Sterility Testing Explained
• Heavy metals (USP <232>/<233>): metal contamination. Peptide Heavy Metals Testing

Which of these your sample needs depends on the compound, how you'll use it and for how long. Plan a peptide test asks eight questions and returns the tests, the labs that run them and what they cost. How to test your peptides covers sending a sample; a base panel costs $150–$325 (verified October 2026), and the page lists what's in it.