Glossary of Peptide Terms: HPLC, CoA, Reconstitution, Bioavailability
Published: 2026-08-03 · Last updated: 2026-08-03
Research peptide vocabulary is a small language of its own. Once you know a few dozen terms, product pages and CoAs stop looking like foreign documents and start being useful. This glossary is organised by topic — chemistry, analytics, handling, pharmacology — rather than alphabetically, so the terms build on each other. Nothing here is dosing guidance. It is plain English definitions for the words you will see repeatedly.
What are the basic chemistry terms?
Amino acid — the building block of peptides and proteins. There are twenty standard amino acids in most biology, plus a handful of non-standard ones used in synthetic peptides. Each one is named and abbreviated (e.g., Alanine = Ala = A).
Peptide — a short chain of amino acids linked by peptide bonds. Usually under about 50 amino acids. Protein — a longer chain, often folded into a complex three-dimensional structure. Sequence — the ordered list of amino acids that make up a peptide, written as a string of letters (e.g., "GHK" for glycyl-histidyl-lysine).
Molecular weight — the mass of a single molecule, usually reported in daltons (Da). Used to identify a peptide on a mass spec report. Salt form — the counterion the peptide is packaged with (acetate, hydrochloride, trifluoroacetate). Affects mass but not sequence. Analog — a modified version of a natural peptide, often with substitutions to change stability or activity.
What do the analytics terms mean?
HPLC (high-performance liquid chromatography) — a technique for separating the components of a mixture and measuring how much of each is present. On a peptide CoA, HPLC reports purity as a percentage: "98.5% pure" means 98.5% of the material in the vial is the target peptide.
Mass spectrometry (mass spec, MS) — a technique that measures the molecular weight of the components of a sample. On a CoA, mass spec confirms identity: the measured mass should match the theoretical mass of the target peptide within a small tolerance. Common variants include LC-MS (liquid chromatography combined with mass spec), MALDI-TOF, and ESI.
CoA (Certificate of Analysis) — the batch-specific analytical report from the lab. Should include batch number, test date, HPLC purity, mass spec identity, and ideally chromatogram and mass spectrum graphs. Our CoA verification guide and HPLC and mass spec guide go deeper on both. Chromatogram — the graph output of an HPLC run showing peaks for each detected component.
What are the handling and packaging terms?
Lyophilised (freeze-dried) — the process by which the peptide is dried under vacuum after freezing, leaving a stable powder. This is why research peptides ship stable at room temperature. Reconstitution — the process of adding a solvent (usually bacteriostatic water) to a lyophilised vial to turn the powder back into a solution.
Bacteriostatic water — sterile water with 0.9% benzyl alcohol as a preservative. The standard solvent for peptide reconstitution because the preservative gives a multi-week fridge shelf life. Sterile water for injection — same thing without the preservative. Shorter shelf life once used.
Aliquot — a small portion of a larger solution, usually stored separately so you can thaw one at a time without freeze-thawing the whole batch. Freeze-thaw cycle — one round of freezing and then thawing a solution. Multiple cycles degrade peptides. See the storage guide for practical detail.
What are the pharmacology terms you will see?
Half-life — the time it takes for the concentration of a compound in the body to drop by half. Written as t1/2. A short half-life means the compound clears quickly; a long half-life means it lingers. Bioavailability — the fraction of an administered compound that reaches its intended site of action intact. Different administration routes produce different bioavailability.
Receptor agonist — a molecule that binds to and activates a specific receptor. Receptor antagonist — a molecule that binds but blocks activation. Dual agonist, triple agonist — a molecule that activates two or three receptors simultaneously (e.g., tirzepatide is a dual GLP-1/GIP agonist).
DAC (Drug Affinity Complex) — a chemical modification that extends the half-life of a peptide by binding to serum albumin in the bloodstream. Used on CJC-1295 to produce a long-acting version. Pegylation — a related concept where polyethylene glycol chains are attached to extend half-life. Not commonly seen in typical research peptide products.
What syringe and dosing terms should I know?
U-100 syringe — an insulin syringe calibrated so that 100 units on the barrel equals 1 mL of fluid. Unit — one tick on a U-100 syringe, equal to 0.01 mL or 10 microlitres. Gauge — the thickness of a needle; higher number means thinner needle.
Milligram (mg) — one thousandth of a gram. Microgram (mcg or µg) — one thousandth of a milligram, or one millionth of a gram. Research peptide vials are usually labelled in mg; individual doses are often calculated in mcg.
Milliliter (mL) — one thousandth of a litre. The standard volume unit for peptide solutions. Microliter (µL) — one thousandth of a millilitre. Sometimes used for very small aliquot volumes. See the insulin syringe guide for the unit-to-mL conversion in practice.
What are the market and vendor terms?
RUO (research use only) — a labelling and sales category meaning the product is sold for lab research and not approved by regulators as a drug for human use. The standard framing for research peptide sales. Non-scheduled — meaning a compound is not on a controlled substances schedule and is not restricted like a drug.
Batch or lot — a single production run of a peptide, typically manufactured, tested, and packaged together. All vials from the same batch share a CoA. Vial strength — the total mg of peptide in a vial. See the vial strengths guide.
Half-kit, full kit — pricing bundles vendors use to sell multiple vials at once, usually at a per-mg discount. Blend — a pre-mixed research product combining two or more peptides in a single vial (e.g., CJC-1295 + ipamorelin). Reconstituted — turned back into a solution by adding bacteriostatic water; see the reconstitution guide for the process. The full catalogue uses this vocabulary throughout.
Questions Canadian buyers ask
What is the difference between HPLC and mass spec?
HPLC measures how pure your peptide is — what percent of the material in the vial is the target compound versus impurities. Mass spec confirms what the peptide is — that its molecular weight matches the target sequence. You want both on a CoA, because a compound can be pure but wrong, or right but impure.
Is "peptide" and "protein" the same thing?
Related but not the same. Peptides are short chains of amino acids, usually under about 50 amino acids. Proteins are longer chains, often folded into complex three-dimensional structures. The boundary is fuzzy — some large peptides are functionally proteins and vice versa — but the shorthand is useful.
What does "lyophilised" mean and why does it matter?
Lyophilised means freeze-dried. The peptide is frozen and then the water is removed under vacuum, leaving a stable dry powder. This is why research peptides ship at room temperature — the dry powder is stable for weeks or months at ambient conditions. Once you add water back (reconstitution), the stability clock starts.
What is bioavailability?
Bioavailability is the fraction of an administered compound that reaches its intended site of action intact. For research purposes, it is a way of describing how much of what you deliver actually makes it to where it can act. Different administration routes produce different bioavailability — the topic is well-covered in pharmacokinetics literature but is not something we make claims about.
Why do CoAs use so many acronyms?
Analytical chemistry has a shared vocabulary of technique abbreviations (HPLC, LC-MS, MALDI-TOF, ESI, etc.). Once you know a few, they are shorthand rather than jargon. The most important ones for a research peptide CoA are HPLC (purity) and mass spec (identity). Everything else is bonus.