Research Peptide Glossary: Key Terms Explained
New to research peptides, or just want a quick reference? This glossary defines the terms you will see most often on product pages, Certificates of Analysis, and lab documentation. Every definition here is written for laboratory research context.
Peptide. A short chain of amino acids linked by peptide bonds. Peptides are smaller than proteins and are widely used in laboratory research.
Amino acids and sequence. Amino acids are the building blocks of peptides. The sequence is the specific order in which they are arranged, and it defines the peptide.
Research Use Only (RUO). A designation meaning a product is intended solely for laboratory research and is not approved for human or animal use. More detail in What Does Research Use Only Mean?
Certificate of Analysis (COA). A laboratory report documenting a compound’s identity and purity for a specific lot. See how to read a COA.
Lot or batch number. A code identifying a single production run. Testing is tied to the lot, so the COA you review should match the lot printed on your vial. You can verify a lot here.
Lyophilized. Freeze-dried. Peptides are typically supplied as a lyophilized powder because it is more stable for storage and shipping. See how to store research peptides.
Reconstitution. The process of dissolving a lyophilized compound into a liquid so it can be worked with in laboratory research.
Bacteriostatic water. A common solvent used to reconstitute lyophilized compounds in a lab setting. It contains a small amount of preservative that inhibits bacterial growth.
Purity. The proportion of a sample that is the intended peptide, as opposed to impurities. It is usually measured by HPLC and shown as a percentage on the COA. More in What Is Peptide Purity?
HPLC (high-performance liquid chromatography). The analytical method most commonly used to measure a peptide’s purity.
Mass spectrometry (MS). A method that confirms a peptide’s identity by measuring its molecular weight and matching it to the expected value.
Endotoxin. A bacterial contaminant that quality-focused labs test for, often using the LAL test. A low endotoxin result is a quality indicator.
Net peptide content. The percentage of a vial’s total mass that is actually peptide, as opposed to residual water, salts, or counterions. It is different from purity.
Third-party testing. Testing performed by an independent laboratory rather than the manufacturer, which adds objectivity to the results.
Milligram (mg) and microgram (mcg). Units of mass. One milligram equals 1,000 micrograms. Vials are typically labeled by the mass of peptide they contain.
Related reading
- What Made in the USA Means for Research Peptides
- What Is Peptide Purity, and How Is It Measured?
- All research guides
All products are sold strictly for research use only (RUO) and are not for human or animal consumption.