Research library
Research terminology
A glossary of analytical, documentation and research terms used across this website. Definitions are general and intended to help readers interpret documentation.
A
- Amino acid analysis (AAA)
- A method in which a peptide is hydrolysed into its constituent amino acids, which are then quantified. Supports identity (composition) and the determination of net peptide content.
- Analytical method
- The specific technique and conditions used to produce a result — for example reverse-phase HPLC with UV detection at 220 nm. Results are only comparable when methods are known.
B
- Batch (lot) number
- An identifier assigned to a quantity of material produced under uniform conditions. It links the material to its documentation, including the Certificate of Analysis.
C
- CAS number
- A unique numeric identifier assigned to a chemical substance by the Chemical Abstracts Service. Useful for unambiguous identification, but note that salts and free forms may have different CAS numbers.
- Certificate of Analysis (COA)
- A document from a testing laboratory reporting analytical results for a specific batch of material.
- Clinical evidence
- Evidence from studies in humans. Its strength depends on design: randomised, blinded, controlled trials rank above open-label or uncontrolled studies and case reports.
- Counter-ion
- The ion that balances the charge of a peptide in its salt form, commonly acetate or trifluoroacetate (TFA). Counter-ion mass is part of the powder weight but not of the peptide.
D
- Deamidation
- A chemical change in which an asparagine or glutamine side chain loses ammonia, forming aspartate/glutamate. A common degradation route for peptides, visible as related substances on HPLC.
- DOI
- Digital Object Identifier — a persistent identifier for a published article, resolvable at doi.org. We record DOIs for citations so they can be checked at source.
E
- Endotoxin
- Lipopolysaccharide from Gram-negative bacterial cell walls. Measured by LAL assay. Relevant for cell-culture and in-vivo research; absence of testing means nothing is known about it.
H
- HPLC
- High-performance liquid chromatography — a separation technique used to assess purity. For peptides, reverse-phase HPLC with UV detection is standard. Purity is reported as the main-peak area percentage.
I
- Identity
- Confirmation that a material is the molecule it is claimed to be, usually by mass spectrometry for peptides. Distinct from purity.
- In vitro
- Literally “in glass” — experiments performed in cells, tissues or biochemical systems outside a living organism.
- In vivo
- Experiments performed in living organisms, most often rodents in preclinical research.
L
- LC-MS
- Liquid chromatography–mass spectrometry — a chromatographic separation coupled to a mass spectrometer. Used to confirm identity by comparing observed and expected molecular mass.
- Lyophilised
- Freeze-dried. Peptides are usually supplied as lyophilised powders for stability.
M
- Mechanism of action
- The biochemical process by which a compound produces an effect. On this website, mechanisms are described as those investigated in cited research, not as established facts about effects in humans.
- Molecular weight
- The mass of one mole of a substance in grams (g/mol). For peptides, average and monoisotopic masses differ slightly; COAs may report either.
N
- Net peptide content
- The proportion of a lyophilised powder that is peptide, as opposed to water, counter-ion and other non-peptide material. Typically 70–90% and distinct from chromatographic purity.
P
- Peer review
- Evaluation of a manuscript by independent experts before publication. A minimum standard for the citations we use, not a guarantee of correctness.
- Preclinical evidence
- Evidence from in-vitro and animal studies. It characterises mechanisms and generates hypotheses but does not establish effects in humans.
- PubChem
- A public chemical database maintained by the US National Library of Medicine. Our primary source for verifying formulae, molecular weights and CAS numbers.
- PubMed ID (PMID)
- The unique identifier of a record in PubMed, the biomedical literature database. Used alongside DOIs to locate citations.
- Purity
- The proportion of a sample that is the intended component, usually measured chromatographically. Does not confirm identity or net content.
R
- Related substances
- Impurities structurally related to the main component — deletion sequences, oxidised or deamidated forms, dimers. Reported on more detailed COAs.
- Research use only (RUO)
- A designation meaning a material is intended for laboratory research and not for human or veterinary use, diagnosis or treatment.
S
- SHA-256 checksum
- A cryptographic fingerprint of a file. Comparing the checksum of a downloaded document with the published value confirms the two files are identical.
T
- Trifluoroacetic acid (TFA)
- An acid used in peptide purification that remains as a counter-ion unless exchanged. It can affect cell-based assays, which is why acetate exchange is often preferred.
V
- Verification status
- The label applied to identifiers and citations on this website: pending (entered, unchecked), verified (checked by an administrator against the source), or rejected (did not pass review).