Peptide documentation is full of abbreviations and lab jargon. This glossary explains the terms you are most likely to meet on a product page, a certificate of analysis or a storage sheet, in plain language. Terms are listed alphabetically.
- Most confusion comes from purity versus content, so start with those entries.
- Many terms relate to testing (HPLC, MS, LAL) and handling (lyophilized, aliquot, reconstitution).
- Use the linked guides for step-by-step detail.
A to C
Acetate salt: a counter-ion left after purification, generally gentler than TFA for biological work.
Aggregation: peptide molecules clumping together, often caused by shaking, heat or poor solubility.
Aliquot: a small portion of a stock solution stored separately to avoid repeated freeze-thaw cycles.
Amino acid: the building block of peptides and proteins.
Amino acid analysis (AAA): a method for measuring net peptide content.
Batch (lot) number: the identifier linking a vial to its test report. See the COA guide.
Bacteriostatic water: sterile water with 0.9% benzyl alcohol. See diluents.
CAS number: a unique numerical identifier for a chemical substance.
Certificate of analysis (COA): the lab report for a specific batch.
Chromatogram: the graph produced by HPLC, with peaks representing components.
Counter-ion: a salt ion (such as trifluoroacetate or acetate) paired with the peptide.
D to L
Diluent: the liquid used to dissolve a peptide.
Endotoxin: a fragment of bacterial cell wall that can disturb cell-based experiments.
EU (endotoxin unit): the unit used to report endotoxin levels.
Freeze-thaw cycle: one round of freezing and thawing, which can damage many peptides.
HPLC: high-performance liquid chromatography, used to measure purity.
Hygroscopic: tending to absorb moisture from the air.
LAL assay: the limulus amebocyte lysate test for endotoxin.
Lyophilized: freeze-dried to remove water, producing a stable powder.
M to R
Mass spectrometry (MS): measures molecular mass to confirm identity.
Molecular weight: the mass of one mole of a compound, in daltons or g/mol.
Net peptide content: the percentage of the powder that is actual peptide, excluding salts and water.
Peptide: a short chain of amino acids. Longer chains are generally called proteins.
Peptide bond: the chemical link between two amino acids.
Purity: the share of the peptide-related material that is the target compound, usually from HPLC.
Reconstitution: dissolving a lyophilized peptide. See the step-by-step guide.
Residual solvents: traces of solvents left from synthesis.
S to Z
Sequence: the order of amino acids in a peptide.
Solid-phase synthesis: the standard method for building peptides step by step on a resin.
Sterile: free of living microorganisms.
Stock solution: a concentrated solution diluted later for use.
TFA salt: trifluoroacetate, the most common counter-ion from HPLC purification.
Theoretical mass: the calculated mass expected for a given sequence.
Vial: the glass container in which a peptide is supplied.
For storage terms such as shelf life, see our storage guide.
Frequently asked questions
What is the difference between purity and content?
Purity describes how much of the peptide material is the target compound. Content describes how much of the powder is peptide at all, as opposed to salts and water.
What does lyophilized mean?
It means freeze-dried: water has been removed under vacuum at low temperature, leaving a stable porous powder.
What is a counter-ion?
A salt ion associated with the peptide after purification, most often trifluoroacetate (TFA) or acetate.
What does RUO mean?
Research use only. Products labelled RUO are intended for laboratory research and not for human or animal use.
Sources and further reading
Products sold by Lodge are intended for laboratory research use only and are not for human or animal consumption. This article is general educational information, not medical or legal advice.
Leave a Reply