Reference

Peptide research glossary.

Plain-English definitions of the 28 terms you'll find on every Pepteed product page and in our research guides — from aliquot to vial.

Aliquot: A measured sub-volume of a reconstituted peptide solution, divided from a larger working stock to limit freeze/thaw cycles. Aliquots are typically stored at −20 °C in low-bind tubes and thawed one at a time as needed.
Amino acid: The 20 organic monomers that link via peptide bonds to form peptides and proteins. Each peptide is described by its sequence (the ordered list of residues, e.g. Gly-His-Lys for GHK).
Acetate salt: A salt form in which acetate counter-ions balance the basic residues of a peptide. Acetate is the preferred salt for laboratory research because it is well tolerated in assays and free of TFA contamination.

Bacteriostatic water (BAC)BAC: Sterile water containing 0.9 % benzyl alcohol as a preservative. Used to reconstitute peptides intended for multi-day laboratory work because the preservative prevents bacterial growth in the vial.

CAS registry numberCAS: A unique numeric identifier assigned by the Chemical Abstracts Service to every catalogued substance. Lets researchers unambiguously identify a peptide across literature, suppliers and databases.
Cold chain: An unbroken temperature-controlled supply chain from synthesis to delivery. For lyophilised peptides Pepteed ships with cold packs and tracking so material arrives within the 2–8 °C / −20 °C envelope it requires.
Certificate of AnalysisCoA: A lot-specific document recording the analytical tests performed on a peptide batch — typically identity (mass spectrometry), purity (HPLC), appearance, and water content. Pepteed releases a CoA for every lot.

Endotoxin: Lipopolysaccharide fragments from gram-negative bacteria. Endotoxin contamination skews cell-culture assays even at low levels; high-grade peptide research uses lots tested for endotoxin via LAL or rFC.

Freeze/thaw cycle: Each round of freezing and thawing a peptide solution. Repeated cycles degrade some peptides; aliquoting on first reconstitution minimises the number of cycles any single working solution sees.

HPLCHigh-Performance Liquid Chromatography: The reference method for measuring peptide purity. The peptide is separated from impurities on a reverse-phase column; the area under its peak as a fraction of the total area gives the % purity figure on the CoA.

Identity confirmation: The analytical step that confirms a peptide's molecular weight matches its expected sequence, performed by mass spectrometry (typically MALDI-TOF or ESI-MS). Recorded on the CoA alongside the HPLC trace.
International UnitIU: A potency-based unit used for some peptides (e.g. HCG) instead of mass, because the biological activity per mg varies with sequence purity. 1 IU corresponds to a fixed activity defined by a WHO reference standard.
In vitro: Latin for "in glass" — experiments performed outside a living organism, on isolated cells, tissues or biochemical components. All Pepteed material is sold strictly for in-vitro research use.

Lot (batch): A discrete synthesis run released under a single identifier. Every vial from the same lot carries the same CoA. Lot numbers let labs trace a result back to the exact material that produced it.
Lyophilisation: Freeze-drying. A frozen peptide solution is placed under vacuum so the water sublimes directly from solid to vapour, leaving a dry powder cake. Lyophilised peptides are shelf-stable at −20 °C for years.

Molar massMW: The mass of one mole of peptide, expressed in g/mol or Da. Calculated from the sequence and confirmed by mass spectrometry. Needed to convert between mass-based and molar-based concentrations in assays.
Mass spectrometryMS: Analytical technique that measures the mass-to-charge ratio of ionised molecules. Used to confirm a peptide's exact mass matches its sequence — the gold standard for identity confirmation on a CoA.

Peptide bond: The covalent amide linkage (-CO-NH-) between the carboxyl group of one amino acid and the amino group of the next. A chain of peptide bonds defines the peptide's backbone.
Purity (HPLC %): The fraction of a peptide lot that is the target sequence rather than synthesis by-products or hydrolysis fragments. Reported as a percentage from the HPLC chromatogram. Pepteed releases lots at ≥ 99 % HPLC purity.

Reconstitution: Dissolving a lyophilised peptide in a solvent (bacteriostatic water, sterile water, or acetic acid) to produce a working solution at a known concentration. Always reconstitute slowly down the inner vial wall, never shake.
Research Use OnlyRUO: A regulatory designation indicating a substance is supplied for in-vitro laboratory research and not for diagnostic, therapeutic or human-consumption use. Every Pepteed product is RUO.

Sequence: The ordered list of amino-acid residues making up a peptide, written from the N-terminus to the C-terminus (e.g. Gly-His-Lys for GHK). The sequence uniquely defines the peptide and its molecular weight.
Solid-Phase Peptide SynthesisSPPS: The dominant method for synthesising research peptides. The peptide is built one residue at a time on an insoluble resin, then cleaved off and purified. Allows precise, high-purity assembly of arbitrary sequences.
Stability: A peptide's resistance to degradation over time at a given temperature. Most lyophilised peptides are stable for 2+ years at −20 °C; once reconstituted, stability drops to days or weeks at 2–8 °C.
Storage: Recommended conditions to preserve a peptide's integrity. Lyophilised: −20 °C, sealed, protected from light. Reconstituted: 2–8 °C short-term, −20 °C for aliquoted long-term storage in low-bind tubes.
Sterile water for injectionSWFI: Water filtered and autoclaved to remove all microbial contamination, with no preservatives added. Used to reconstitute peptides when a preservative-free solution is required for downstream assays.

TFA (trifluoroacetic acid)TFA: A strong acid used during SPPS cleavage. Some peptides remain as TFA salts after purification, which can interfere with cell-culture assays. Higher-grade material is supplied as the acetate salt instead.

Vial: The sealed glass container in which lyophilised peptide is supplied, capped with a rubber stopper and aluminium crimp. The stopper allows reconstitution solvent to be added through a needle without breaking the seal.

Definitions are written for an in-vitro research audience and are not medical, clinical or regulatory advice. For authoritative biochemical references see PubChem, IUPAC and your local pharmacopoeia.