What HPLC measures: purity
High-performance liquid chromatography separates the components of a sample as they pass through a column at different rates. The resulting chromatogram shows peaks; the area of the target peak relative to the total indicates purity — how much of the sample is the intended compound versus impurities.
What mass spectrometry measures: identity
Mass spectrometry ionizes the molecule and measures its mass-to-charge ratio, returning a precise molecular weight. Comparing the measured mass to the theoretical mass of the target peptide confirms identity — that the compound is what the label claims.
Why a COA needs both
Purity without identity is meaningless: a sample can be 99% pure of the wrong molecule. Identity without purity is incomplete: you confirm the right peptide is present but not how much contamination accompanies it. Reading them together is the only way to know you have a high-purity, correctly identified reagent.
Reference standards and accreditation
The most rigorous testing is performed by independent laboratories against reference standards, ideally under recognized accreditation. Independent verification removes the conflict of interest inherent in manufacturer self-testing.
See it in practice
Every Ethos Bio compound ships with an independent, mass-spec-verified Certificate of Analysis. Browse the public COA library.
Frequently asked questions
What is the difference between HPLC and mass spectrometry for peptides?
HPLC measures purity (what percentage of the sample is the target compound), while mass spectrometry confirms identity (that the molecular weight matches the intended peptide). A complete COA reports both.
Can a peptide be high purity but the wrong compound?
Yes — that is exactly why mass-spectrometry identity confirmation is required alongside HPLC purity. A sample can be 99% pure of an unintended molecule, which only an identity check would catch.
Which is more important, HPLC or mass spectrometry?
Neither alone is sufficient. Identity (MS) and purity (HPLC) answer different questions, and a trustworthy Certificate of Analysis includes both with stated acceptance criteria.