A reference glossary of terms commonly used across peptide research documentation, testing reports, and supplier listings. Useful for researchers who are new to evaluating COAs, supplier specifications, or compound naming conventions.
Testing & Quality Terms
HPLC (High-Performance Liquid Chromatography) — The standard analytical method for measuring peptide purity. It separates the components of a sample and reports what proportion corresponds to the target compound versus impurities. See our guide to reading a COA for a full explanation.
Mass Spectrometry — An analytical method that measures a compound’s molecular weight to confirm its identity. Used alongside HPLC, since purity and identity are separate measurements — one does not confirm the other.
Certificate of Analysis (COA) — A document issued by a testing laboratory reporting the results of quality control testing on a specific manufacturing batch.
Purity — The proportion of a sample that corresponds to the correct target compound, typically expressed as a percentage from HPLC analysis. A purity of 98% means 98% of the detected peptide-related material is the correct sequence.
Net Peptide Content (NPC) — A separate measurement from purity, indicating what proportion of a vial’s total labelled weight is actual peptide versus counter-ions, moisture, and other residual material from synthesis. A vial labelled “5mg” with 80% NPC contains approximately 4mg of actual peptide.
Endotoxin Testing — A screening test for bacterial endotoxins, typically reported in EU/mg (endotoxin units per milligram), relevant to assessing contamination risk from the manufacturing process.
ISO 17025 — An international accreditation standard for testing and calibration laboratories. A relevant marker when assessing whether a testing lab is independently credible.
Compound & Chemistry Terms
Lyophilised — Freeze-dried. The standard form in which research peptides are supplied and shipped, since the dry powder state is significantly more stable than a reconstituted solution.
Reconstitution — The process of dissolving a lyophilised peptide in a solvent (such as bacteriostatic water) prior to use. We do not provide reconstitution ratios or guidance, as our products are supplied for research use only.
CAS Number — A unique numerical identifier assigned by the Chemical Abstracts Service to a specific chemical compound, used to unambiguously identify a substance regardless of what name or brand it’s sold under.
Molecular Weight (M.W.) — The mass of a single molecule of a compound, typically expressed in Daltons (Da), used in mass spectrometry to confirm identity.
Sequence — The specific order of amino acids that makes up a peptide, often written using three-letter amino acid abbreviations (e.g. Gly-His-Lys for GHK).
Counter-ion — A charged ion that accompanies a peptide in its commercial form, most commonly acetate. Affects the net peptide content of a given vial weight.
Synthetic Analogue — A laboratory-synthesised compound designed to replicate or closely resemble the structure of a naturally occurring molecule.
Regulatory Terms
Research Use Only (RUO) — A labelling standard indicating a product is supplied exclusively for laboratory research, not for human or veterinary administration.
MHRA — The Medicines and Healthcare products Regulatory Agency, the UK’s regulator responsible for licensing medicines. None of the compounds discussed on this site hold MHRA marketing authorisation.
Misuse of Drugs Act 1971 — The primary UK legislation controlling scheduled drugs. Most research peptides discussed on this site are not scheduled under this Act. See our FAQ for more detail.
Human Medicines Regulations 2012 — UK legislation that prohibits selling or marketing a product for human medicinal use without MHRA marketing authorisation.
Common Compound Abbreviations
- BPC-157 — Body Protection Compound 157
- TB-500 — Thymosin Beta-4 fragment
- GHK-Cu — Glycyl-Histidyl-Lysine-Copper complex
- CJC-1295 — A synthetic GHRH analogue
- NAD+ — Nicotinamide Adenine Dinucleotide
For detailed mechanistic information on these and other compounds, see our Research Peptides UK: Complete Buying Guide, which links to every compound-specific article on this site.
This glossary is provided for general informational and educational purposes only. All products supplied by Claripep Ltd are intended strictly for laboratory research applications.