L-valine
Enable an agent to identify L-valine, assess the condition and quality of a particular sample, and determine its suitability for an evidenced intended use.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to identify L-valine, assess the condition and quality of a particular sample, and determine its suitability for an evidenced intended use.
L-valine is the proteinogenic (S)-enantiomer of 2-amino-3-methylbutanoic acid, a branched-chain α-amino acid that humans require from dietary sources.
It can be Reconcile a label and analytical identity with the registered L-valine concept.; Request separate chemical-assay and stereochemical-purity evidence.; Calculate a weighed amount or solution concentration using the documented assay basis.; Compare a lot against an intended-use specification and record acceptance or quarantine.; Select documented storage, dissolution and handling conditions.; Trace an uncertain or changed sample back to its lot, sampling history and supporting records..
Distinguishing features
Require evidence of the L-enantiomer: the word 'valine' alone does not establish stereochemical identity. [ChEBI](https://www.ebi.ac.uk/chebi/CHEBI%3A46418)
Match both composition and structure: L-valine has formula C5H11NO2; a formula match alone cannot establish connectivity or stereochemistry. [ChEBI](https://www.ebi.ac.uk/chebi/CHEBI%3A46418)
Distinguish free L-valine from a covalently incorporated valyl residue or derivative. [ChEBI](https://www.ebi.ac.uk/chebi/CHEBI%3A46418)
Identify whether a record describes L-valine, its zwitterionic representation, L-valinium or L-valinate before reconciling identifiers. [ChEBI](https://www.ebi.ac.uk/chebi/CHEBI%3A46418)
Scope
+ Stereochemical identity and reconciliation of substance identifiers
+ L-valine assay, enantiomeric purity, impurities and declared grade
+ Solid and dissolved sample states under recorded conditions
+ Measurement methods, reference standards and lot provenance
+ Storage, handling and intended-use qualification
- D-valine and DL-valine as independently identified substances
- Separately identified salts, derivatives and peptides containing valine residues
- Finished supplements, foods, feeds and pharmaceutical formulations
- Manufacturing processes and production equipment
- Organism-level metabolism, nutritional requirements and clinical treatment decisions
Characteristics
- Stereochemical identity
- L confirmed; stereochemistry unresolved; conflicting evidence Prevents an unspecified valine label from being accepted as proof of L-valine.
- Substance identifier agreement
- Registry id linked to verified CAS, PubChem, EC and ChEBI records with source and chemical form Detects identifiers that refer to a different stereoisomer, mixture or chemical species.
- L-valine assay
- % mass fraction, with as-is or dry basis, method and uncertainty Determines the actual amount of qualified substance in a sample.
- Enantiomeric composition
- L and D fractions in %; enantiomeric excess in % when applicable; detection limit Separates stereochemical purity from total valine content.
- Water content
- % mass fraction with method; distinguish water-specific measurement from loss on drying Supports assay-basis conversion and assessment of storage-related change.
- Impurity profile
- Named impurities in mg/kg or %; unidentified peaks and method limits Supports use-specific acceptance instead of relying on a single purity number.
- Physical presentation
- Solid or solution; appearance; solid-form evidence or solvent composition Determines which sampling, dissolution and handling operations are appropriate.
- Solution concentration and acidity
- g/L or mol/L and pH, with solvent, temperature and preparation basis Makes solution preparation and comparisons reproducible.
- Solubility and thermal behavior
- Solubility in g/L with solvent and temperature; thermal events in °C with method and event type Supports dissolution and temperature decisions without confusing decomposition with melting or boiling.
- Grade and release status
- Declared grade and specification revision; unassessed, accepted, quarantined or rejected for a named use Ties suitability to evidence and an intended application.
- Hazard and use authority
- Applicable SDS, GHS assessment, exposure-limit source and use rules with jurisdiction and revision Prevents unsupported transfer of a supplier's classification or use permission to another sample.
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 5 bundles · 9 layers · 16 findings · 24 questions.
L-valine identity Establish the molecular and stereochemical identity behind a label or sample.
A valine name or total-valine measurement does not by itself establish L-valine.
Structure and stereochemistry
Separate chemical identity from evidence of enantiomeric composition.
Identity evidence
Record the structural reference and analytical evidence used to identify the sample as L-valine.
- Which structure and stereochemical reference define L-valine for this record? definition
- Which measurements establish valine identity, and which independently establish its L configuration or enantiomeric composition? measurement
Identifier and species boundaries
Resolve identifier agreement without collapsing distinct chemical forms.
Registry crosswalk
Attach sourced identifiers to the chemical entity they actually denote and explain related-species links.
- Which CAS, PubChem, EC and ChEBI records have been checked against the L-valine structure? provenance
- Does the supplied record denote free L-valine, a protonation-state representation, a salt, a derivative or a containing mixture? boundary
L-valine lot quality Determine how much L-valine a lot contains and whether its accompanying material is acceptable.
Chemical assay, enantiomeric purity and application-specific impurity limits answer different qualification questions.
Assay and enantiomeric purity
Keep total content, L/D composition and reporting basis distinct.
Qualified content
Make quantitative content claims interpretable through methods, calibration and sample basis.
- Does the reported assay measure total valine or specifically L-valine, and is it reported on an as-is or dry basis? measurement
- What method quantifies D-valine, and what detection limit supports the claimed enantiomeric purity? measurement
Impurities, grade and traceability
Connect use-relevant impurity evidence to a particular lot and specification.
Lot qualification evidence
Record the evidence behind grade claims and identify missing qualification data.
- Which lot-specific certificate, specification revision and sampling record support the declared grade? provenance
- Which limits for related amino acids, water, residual solvents, elemental or microbial contamination apply to the intended use, and which results remain missing? action
L-valine physical state Describe solid and solution conditions sufficiently to support reproducible handling and preparation.
Dissolution, concentration and thermal decisions require conditions and measurement methods alongside values.
Solid condition and thermal events
Characterize the supplied solid and distinguish observed thermal events.
Solid-state evidence
Record relevant solid-form, moisture and thermal observations without assuming universal constants.
- What evidence describes the sample's solid form, water content, particle characteristics and any change during storage? measurement
- Do reported thermal values describe melting, decomposition or another event, and under what atmosphere, pressure and heating method? measurement
Dissolution and solution condition
Connect solubility and solution measurements to a defined preparation.
Reproducible solution
Capture the conditions needed to prepare and verify an L-valine solution.
- What solubility evidence applies to the selected solvent, temperature, pH and concentration range? measurement
- What assay-corrected mass, final volume and verification steps are required for the intended solution? action
L-valine use and handling Translate sample evidence into justified handling and intended-use decisions.
Identity alone cannot establish storage requirements, hazard status or suitability for a particular application.
Storage and exposure controls
Ground storage and handling choices in applicable documentation and sample condition.
Documented handling envelope
Associate handling decisions with the actual material, current documentation and observed condition.
- Which SDS revision supports the GHS classification and exposure controls for this L-valine material, and are applicable exposure limits documented? provenance
- Which packaging, storage conditions, retest dates and observed changes require continued use, retesting or quarantine? action
Intended-use release
Assess the substance lot against a named application without taking ownership of a finished product or treatment.
Application-specific disposition
Record the application, governing requirements and evidence supporting the lot's disposition.
- What intended use and jurisdiction determine the applicable L-valine quality and authorization requirements? boundary
- Does the lot satisfy those requirements, and which unresolved evidence prevents release? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This description is recalled knowledge; no sources were consulted.
- Listed grades describe intended-use and quality distinctions, not different molecular species; their specifications require verification.
- Verify current compendial requirements, regulatory permissions, hazard classifications and condition-dependent physical constants before adding them.
- Which of these check these first hold for the sense of L-valine this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Pharmaceutical grade
- Food grade
- Feed grade
- Analytical reagent grade
- Which of these kinds and varieties hold for the sense of L-valine this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- CAS Registry Number - 72-18-4 - Identifies L-valine specifically, rather than D-valine or racemic valine.
- IUPAC nomenclature - (2S)-2-amino-3-methylbutanoic acid - Specifies the configuration of its single stereogenic centre.
- Molecular formula - C5H11NO2 - Does not distinguish stereoisomers.
- Amino-acid residue codes - Val; V - Three-letter and one-letter codes used for valine residues in protein sequences.
- Which of these identifiers and schemes hold for the sense of L-valine this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Component of amino-acid mixtures for nutritional formulations.
- Supplementation of animal feed to meet amino-acid requirements.
- Nutrient in cell-culture and microbial growth media.
- Starting material for peptide synthesis.
- Reference material for amino-acid analysis.
- Which of these real-world use hold for the sense of L-valine this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Molar mass - 117.15 - g/mol
- Which of these typical measurements hold for the sense of L-valine this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Incorrect stereochemical composition can make material unsuitable for applications requiring L-valine.
- Chemical impurities, microbial contamination or an unsuitable grade can make material unacceptable for nutritional or pharmaceutical use.
- Heating can cause decomposition, so a reported high-temperature transition should not automatically be interpreted as clean melting.
- Which of these failure modes and hazards hold for the sense of L-valine this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Requirements for use in foods, feeds and pharmaceutical preparations depend on jurisdiction and intended application.
- Which of these regional variation hold for the sense of L-valine this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Valine - Valine without a stereochemical qualifier can denote the amino acid generically; L-valine specifies the S-enantiomer.
- D-valine - Has the opposite, R configuration at the α-carbon.
- DL-valine - Is a racemic mixture of L-valine and D-valine.
- L-leucine - Has an isobutyl side chain, whereas L-valine has an isopropyl side chain.
- L-isoleucine - Has a sec-butyl side chain and two stereogenic centres, whereas L-valine has one.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of L-valine this model covers, and on what evidence? provenance
What the second pass must settle
- Which verified CAS and EC identifiers complement the structural reference, and how should zwitterionic and protonation-state records be linked without creating duplicate substance models?
- Which analytical methods and reference standards adequately distinguish L-valine from D-valine and structurally related impurities for each intended grade?
- Which measured solubility, acid-base and thermal data are reliable under specified conditions, including whether a reported boiling point is experimentally meaningful?
- Which current specifications and jurisdiction-specific permissions apply to the intended research, food, feed or pharmaceutical use?
- What lot-specific stability, packaging and exposure evidence supports storage periods, retest triggers and handling controls?