What each analytical test tells you about a peptide — and what it doesn’t.
Separates the target peptide from synthesis byproducts. Reports purity as a percentage of UV-absorbing peaks. Does not capture water, counterion salts, or non-UV contaminants. A 99% HPLC-pure peptide can be 75–85% peptide by weight.
Measures molecular weight. Compares observed vs theoretical to confirm you have the right compound. HPLC + MS together = “how pure” + “what it is.” One without the other is an incomplete picture.
Hydrolyzes the peptide and quantifies each amino acid. Confirms composition and determines net peptide content — the actual weight percentage of peptide in the powder. Critical for accurate dosing in compounding.
Tests for bacterial endotoxins that cause severe reactions when injected. Required for any injectable-grade peptide. No LAL results = not injectable-grade, regardless of other claims.
Peptide synthesis uses organic solvents (DMF, DCM, TFA, acetonitrile). Gas chromatography confirms they’ve been removed to safe levels per ICH Q3C guidelines.
Screens for lead, arsenic, cadmium, mercury from manufacturing equipment or raw materials. USP <232>/<233> sets the limits.
A single test tells a partial story. A complete analytical profile requires HPLC + MS + AAA + LAL + GC + ICP-MS. The more tests on the COA, the more confidence you have. Full COA verification guide →