Glossary
Use this research peptide glossary to read a specification, vial label or certificate of analysis. Jump to identity and composition, analytical records or quantities and records. For the name of a particular molecule, use the compound index.
Identity and composition
| Term | Meaning and further reading |
|---|---|
| Peptide | A molecule containing two or more amino-acid residues joined by peptide bonds. Peptide basics. |
| Sequence | The order of residues along a chain. A one-letter sequence conventionally runs from N-terminus to C-terminus. Names and identifiers. |
| Terminal group | The chemical group at an end of the chain. A C-terminal acid and a C-terminal amide identify different forms. Identity records. |
| Salt or counter-ion | A salt contains charged species. The counter-ion balances charge and can contribute to the supplied mass. Salt forms. |
| Complex | An association of chemical species, such as a metal ion coordinated by a peptide. Record which complex the specification identifies. Copper complexes. |
| Blend | Two or more named components supplied in one presentation. Record the amount and identity of each component. Single compounds and blends. |
Peptide terms describe how residues are joined and arranged. The chemistry at each end and the supplied form can add information beyond the residue sequence. See IUPAC’s definitions of a peptide and a residue. [1]
Analytical records
| Term | Meaning and further reading |
|---|---|
| Identity | The assignment of a sample to a defined chemical entity. Check which test supports that assignment. Identity, purity and assay. |
| Purity | The proportion attributed to the target on a stated measurement basis. Ask how the analytical method determines that proportion. Purity versus identity. |
| HPLC area percentage | An integrated chromatographic peak’s share of the stated total peak area under that method. It does not directly give milligrams per vial. HPLC. |
| Assay | A determination of a defined analyte on a stated basis. Read the result with its units, method and sample reference. Assay and content. |
| Net peptide content | The proportion of sample mass attributed to peptide material on the declared basis. Depending on the method, related peptides may contribute. Net peptide content. |
| Acceptance criterion | A limit, range or other requirement against which a test result is assessed. Acceptance and OOS. |
| CoA | A certificate of analysis. Match the product, lot, tests, results and criteria to the container being assessed. CoA guide. |
| Endotoxin | A lipopolysaccharide associated with Gram-negative bacteria. An endotoxin result and a sterility test address different attributes. Three microbiological attributes. |
On a certificate, read the test name, method, result, unit and acceptance criterion together. A result can meet a stated limit while another property of the same material remains unmeasured. [3]
Quantities and records
| Term | Meaning and further reading |
|---|---|
| Nominal fill | The declared quantity for the presentation. A measured target-content result needs a defined analyte and method. Appearance and fill. |
| Mass concentration | Mass of the specified constituent divided by final solution volume, for example mg/mL. Mass and molarity. |
| Molar mass | Mass divided by amount of substance for a defined entity, commonly expressed in g/mol. Unit conversions. |
| Amount concentration (molarity) | Amount of the specified constituent divided by final solution volume, commonly mol/L. Mass and molarity guide. |
| Lot | A batch designation connecting material with specified records. Give individual containers separate local identifiers where needed. Lot traceability. |
| Chain of custody | A record of who handled or transferred an identified sample and when. Sample traceability. |
| Retest date | The date at which material is due for reassessment under the associated conditions and procedure. Storage evidence. |
| Temperature excursion | An exposure outside the conditions that apply to the material. Record its evidence and the limits of what is known. Excursion records. |
| Aliquot | A measured portion taken from a larger sample or preparation. Retain the parent identifier and the portion’s own history. Aliquot records. |
| Research use only | A statement about intended supply and use. Check the applicable policy and assess chemical identity separately. RUO meaning. |
Look at the denominator. Milligrams per millilitre describes mass concentration. Grams per mole describes molar mass. Moles per litre describes amount concentration. The material and final volume must be defined before moving between these quantities. [2]
For a label beside a product name, open the research catalogue to check the listed presentation. The batch and lot log connects the supplier record with an individual container.
Supporting checks
| Resource | Why open it |
|---|---|
| Product Specification and Identity Standards | Check which tests, criteria and quantity basis a specification defines. |
| Research Use and Buyer Eligibility Policy | Read the UK research-buyer and manual-order-review conditions. |
| Guides & Resources | Choose another scientific, analytical or procurement guide. |
Sources and scope
- IUPAC–IUB: Amino-acid and peptide nomenclature, 3AA-11 to 3AA-13 Sections 3AA-11 to 3AA-13 define peptides, residues and terminal groups.
- NIST · Guide to the SI, chapter 8 Sections 8.6.4 and 8.6.5 define molar mass and amount concentration and give their units.
- ICH Q6A: Specifications, Test Procedures and Acceptance Criteria for New Drug Substances and New Drug Products Q6A describes specifications, analytical procedures and acceptance criteria in a pharmaceutical context.