Peptide Purity Testing Explained: HPLC, Mass Spec, Endotoxin (PH)

Shopping for peptides in the Philippines and seeing a purity percentage on the listing? Here is what that number actually measures. Purity is usually measured by HPLC, high performance liquid chromatography. A column separates the sample into its parts.

And a detector draws a chart called a chromatogram. Each component shows up as a peak. The main peak should be the target peptide. Smaller peaks are impurities, often deletion sequences: copies missing an amino acid or more.

Purity is the main peak's share of everything the detector sees, usually material absorbing ultraviolet light at 220 nanometres. But HPLC does not prove what that peak is. That is the job of mass spectrometry, which measures molecular mass to confirm identity. Endotoxin testing looks for fragments of bacterial cell walls.

The classic LAL test uses an extract from horseshoe crab blood, and reports endotoxin units, or EU. Heavy metals screening checks for lead, mercury, arsenic and cadmium, using instruments like ICP-MS. So why is purity alone not everything? It says nothing about identity, endotoxin or metals.

And powders hold water and counter-ions, so purity is not how much peptide is in the vial. Many buyers here pay by GCash or Maya before a vial arrives. So in Makati or Cebu, ask which tests a report actually covers. If you are sourcing research peptides in the Philippines, Primara Labs publishes independent lab reports you can verify yourself.

Guides at primaralabs.com.