New to research peptides? This glossary defines the terms you’ll meet on listings and Certificates of Analysis — in plain English.
Quality & testing
Certificate of Analysis (COA) — A lab document reporting the measured quality of a specific batch: purity, identity, and other parameters. Should be batch-specific.
HPLC (High-Performance Liquid Chromatography) — A method that separates a sample to measure purity, shown as peaks on a chromatogram.
Mass spectrometry (MS) — Measures molecular mass to confirm identity (the molecule is what the label says).
Purity — The percentage of the target peptide among peptide-related species, by HPLC. A common high standard is ≥99%.
Net peptide content — How much of the vial’s mass is actually peptide (vs. salt and water); often 80–95%.
Chromatogram — The graph from HPLC; one tall, sharp peak signals high purity.
Third-party / accredited lab — An independent, audited lab whose results are more credible than in-house figures.
Composition & form
Lyophilized — Freeze-dried into a stable powder by removing most water.
Counter-ion — The salt form a peptide ships in, usually acetate or TFA (trifluoroacetate); affects net peptide content.
Karl Fischer (KF) — A titration that measures residual water in the powder.
Endotoxin — Bacterial contaminants sometimes reported on a COA; lower is better.
Sequence — The ordered chain of amino acids that defines the peptide.
Molecular weight (MW) — The mass of one mole of the compound (g/mol); needed to convert to molar units.
Concentration math (in-vitro)
Molarity (M) — Moles per litre; counts molecules. mM = millimolar, µM = micromolar.
Stock solution — A concentrated solution you later dilute.
Dilution (C₁V₁ = C₂V₂) — The equation for making a weaker solution from a stronger one.
mg/mL — Milligrams of solute per millilitre of solvent; a mass-per-volume concentration.
Logistics
Batch / lot number — A code identifying a production run; match it to your COA and vial.
Cold-chain — Temperature-controlled handling/shipping for products that need it.
Research use only (RUO) — Sold strictly for laboratory research; not for human or veterinary use.
Key takeaways
- HPLC = purity, MS = identity, COA = the batch report tying it together.
- Lyophilized powder is stable when kept cold, dark and dry.
- Net peptide content and counter-ion explain what’s really in the vial.
FAQ
What does “lyophilized” mean in one sentence? Freeze-dried into a dry, stable powder by removing water.
What’s the difference between mM and µM? 1 mM = 1000 µM. Both are molar concentrations; mM is a thousand times stronger than µM.
What does RUO mean? Research use only — the product is for laboratory research, not for human or veterinary use.
Browse verified research peptides
Every batch we ship is independently tested by Janoshik Analytical — HPLC for purity, mass spectrometry for identity — with a batch-matched Certificate of Analysis you can verify yourself. Browse the catalog → · See the latest COAs →
*For laboratory and research use only. Not for human or veterinary use, consumption, or administration. Nothing in this article is medical advice or a claim that any compound treats, cures, or prevents any condition.*