HPLC purity, explained
"≥ 98% purity" is the headline figure on most peptide COAs — and the most misread. It's a useful number, but it answers one specific question and not several others. Here's exactly what it does and doesn't tell you.
what HPLC actually measures
High-performance liquid chromatography (HPLC) separates the components of a sample as they pass through a column, producing a trace (a chromatogram) with a peak for each component. Purity is reported as the target peptide's peak area as a percentage of the total peak area. A ≥ 98% result means the target peak accounts for at least 98% of what the detector saw; the remaining ≤ 2% is related peptides and process impurities.
what a high purity number does tell you
- The sample is mostly the intended peptide, with few chromatographically-separable impurities.
- A clean chromatogram — one dominant, well-resolved peak — supports the number visually.
- Batch-to-batch consistency, when purity holds across lots.
what it does not prove
- Identity. Purity says the main peak is dominant, not which molecule it is. Identity is confirmed separately by LC-MS (mass spectrometry) — always read the two together.
- How much is in the vial. Purity is a relative figure. A perfectly pure sample can still be underfilled — that's why the COA also reports peptide content (typically specified 95–105% of label).
- Sterility or endotoxin. Those are separate tests (e.g. the LAL endotoxin assay on the safety panel), not part of the purity figure.
- Anything a co-eluting impurity hides. Two components that leave the column at the same time can sit under one peak; method quality and the mass-spec confirmation are what guard against this.
read purity in context
A meaningful purity result comes with three companions: an LC-MS identity confirmation, a peptide content figure, and the chromatogram itself. A purity percentage quoted alone — no chromatogram, no identity, no content — is a claim, not evidence. See how to read the full COA.
research use only
This explains an analytical measurement; it is not usage guidance. Veyvora compounds are supplied for laboratory research use only — not medicines, and not for human or veterinary consumption.
