citric acid
Enable an agent to recognise citric acid, assess the identity and condition of a particular material, and determine its suitability for a proposed 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 recognise citric acid, assess the identity and condition of a particular material, and determine its suitability for a proposed use.
Citric acid is a weak, triprotic organic acid with molecular formula C6H8O7 and three carboxyl groups, occurring naturally in organisms and participating through its conjugate base, citrate, in the citric acid cycle.
It can be Verify whether an incoming material is citric acid in its declared hydration form and grade.; Calculate citric acid content or prepare a target solution using the correct assay and hydration basis.; Evaluate a lot against the specification required for a proposed use.; Assess whether stated conditions support acidification, buffering or metal sequestration.; Select supported storage and handling measures and flag material requiring retesting or quarantine..
Distinguishing features
Identity evidence must support citric acid's molecular composition C6H8O7 and connectivity, rather than merely identifying a sour or acidic material.
Anhydrous citric acid and citric acid monohydrate must be distinguished through declared form and appropriate water or solid-state evidence; water content alone may include adventitious moisture.
A material supplied as a citrate salt must be distinguished through counterion identity and composition, rather than treated as another grade of citric acid.
Citric acid dissolved in water must be distinguished from neat citric acid through solvent content and concentration; solution pH alone does not establish identity or concentration.
Food, pharmaceutical and technical grades require evidence against their applicable specifications; a shared chemical name does not establish interchangeability.
Scope
+ Chemical identity and identifiers qualified by anhydrous or hydrated form
+ Composition, assay basis, impurities and documented grade
+ Solid-state condition, water content and behaviour in solution
+ Acidity, buffering and metal-binding behaviour under specified conditions
+ Handling constraints, compatibility and evidence of suitability for a stated use
- Citrate salts and citrate esters as independently identified substances
- Complete food, cleaning, cosmetic or pharmaceutical formulations
- Industrial fermentation, recovery and purification process models
- The citric acid cycle and organism-level metabolism
- Clinical treatment decisions and finished-product regulatory authorisation
Characteristics
- Chemical identity and identifier mapping
- Verified name, molecular structure, CAS number, PubChem CID and EC number where applicable, each qualified by represented form Prevents records for hydrates, citrate salts or formulated products from being silently merged.
- Hydration form
- Anhydrous; monohydrate; mixed or unresolved form Affects formula mass, assay interpretation and the mass required to supply a specified amount of citric acid.
- Citric acid assay
- % mass fraction, with method and as-received, dried or anhydrous reporting basis Supports valid comparisons and dosing calculations without confusing purity with water correction.
- Water content
- % mass fraction, with analytical method and sample conditioning Helps assess hydration, moisture uptake and compliance with the declared form.
- Grade and specification
- Supplier grade linked to a named specification, edition and lot-specific evidence Determines which suitability claims are supported for a proposed application.
- Impurity profile
- Named analytes in mg/kg or % mass fraction, with methods and detection limits Distinguishes material that meets assay requirements from material that also meets use-specific contaminant limits.
- Physical presentation and condition
- Crystals, powder or solution; particle-size distribution where relevant; free-flowing, caked, discoloured or otherwise altered Influences dissolution, transfer, sampling and the need for investigation before use.
- Solution concentration and acidity
- g/L, mol/L or % with explicit basis; pH and titratable acidity with temperature and method Separates the amount of citric acid present from its measured acid behaviour in a particular solution.
- Condition-dependent physical properties
- Solubility in g/L or g/100 g solvent; density in kg/m³; thermal transitions in °C, with form, conditions and decomposition observations Supports dissolution, storage and heating decisions without treating every thermal event as melting or assuming a usable boiling point.
- Metal-binding context
- Metal species, concentrations, pH, competing ligands and observed or validated binding outcome Determines whether citrate formation supports the intended sequestration or cleaning effect under actual conditions.
- Handling and regulatory classification
- Applicable hazard classification, exposure-limit status and use restrictions, qualified by jurisdiction, material form, concentration and source date Connects handling and permitted-use decisions to the actual material and applicable evidence.
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.citric-acid
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 19 findings · 29 questions.
Citric acid identity Establishes which chemical entity and hydration form a record represents.
Citric acid, its hydrate and citrate-containing materials can share informal labels while requiring different interpretation.
Molecular identity
Connects the registered thing to chemical identity evidence.
Identity evidence
Record the evidence needed to identify citric acid beyond acidity, appearance or a supplier label.
- Which structure record and analytical identity tests establish that this material is citric acid? definition
- Which authoritative records support its identifiers, and what exact chemical form does each identifier represent? provenance
Hydrate and citrate boundaries
Separates hydration variants from salts and formulated mixtures.
Represented material form
Record whether the material is anhydrous acid, monohydrate, a solution or an unresolved material, with explicit salt boundaries.
- What evidence distinguishes the declared hydrate from anhydrous citric acid carrying absorbed moisture? measurement
- Does the supplied material contain counterions or other ingredients that require a citrate-salt or formulation model? boundary
Assay, grade and impurities Makes compositional quality and application-specific grade claims assessable.
Citric acid assay, hydration and impurity limits jointly determine whether a lot is suitable for use.
Assay and water basis
Relates measured acid content to water content and reporting conventions.
Comparable acid content
Record assay and water results with enough context to calculate and compare actual acid content.
- Is the citric acid assay reported as received, on a dried basis or on an anhydrous basis, and by which method? measurement
- How must hydration form, measured water and assay basis be reconciled before calculating a required mass? action
Grade conformance
Tests grade claims against explicit specifications and lot evidence.
Supported grade claim
Record the applicable specification, required impurity checks and evidence supporting the claimed grade.
- Which specification and edition define this lot's claimed food, pharmaceutical, analytical or technical grade? provenance
- Which impurity, residue and microbiological requirements apply to the intended use, and which lot results demonstrate compliance? measurement
Physical state and stability Describes how hydration, particle condition, dissolution and heating affect the material.
A chemically identified lot can still behave differently because of moisture exposure, physical presentation or thermal history.
Solid condition
Tracks the condition of crystalline or powdered citric acid.
Moisture and particle condition
Record particle characteristics and observed changes relevant to sampling, flow and dissolution.
- What particle-size distribution, caking and visible changes characterise the current lot? measurement
- What storage history and analytical evidence determine whether observed moisture-related changes require retesting? action
Dissolution and thermal behaviour
Qualifies solubility and thermal observations by material form and test conditions.
Conditioned property evidence
Record properties that support preparation and temperature-control decisions without conflating dehydration, melting and decomposition.
- What solubility and dissolution evidence applies to the selected solvent, temperature, hydration form and particle size? measurement
- Which observed thermal events are dehydration, melting or decomposition, and is a boiling-point value meaningful under the stated conditions? measurement
Acid and citrate function Connects solution conditions to acidification, buffering and metal binding.
Citric acid's useful behaviour depends on concentration, acid-base state and other substances present.
Acid-base behaviour
Distinguishes concentration, measured acidity and buffering requirements.
Acidification and buffering
Record conditions needed to predict or verify the intended acid-base effect.
- What concentration, temperature, pH and titratable acidity describe the solution being evaluated? measurement
- What validated acid-base data and matrix conditions support the proposed acidification or citrate-buffer preparation? action
Metal interactions
Characterises context-specific interactions with metal species and contacted materials.
Sequestration and material response
Record whether metal binding produces the intended effect and how contacted materials respond.
- Which metal species, pH range and competing ligands determine the expected complexation behaviour? measurement
- What evidence supports the intended cleaning or sequestration effect while establishing compatibility with the contacted material? action
Handling and use eligibility Links the actual citric acid material to handling requirements and permitted applications.
Handling and use decisions require evidence specific to form, concentration, grade and jurisdiction.
Exposure and storage
Assesses powder, solution and contact conditions using applicable safety information.
Supported handling conditions
Record applicable hazard information, exposure controls and storage compatibility.
- Which current safety source establishes the classification and exposure-limit status for this material and jurisdiction? provenance
- What controls and storage conditions follow from its powder or solution form, concentration, handling operation and documented incompatibilities? action
Application eligibility
Separates substance-level suitability from approval of a finished product or process.
Use-specific evidence
Record the evidence needed to accept a citric acid lot for a named application.
- What grade, traceability and jurisdiction-specific conditions must this material meet for the proposed application? action
- Which remaining decisions depend on the finished formulation, manufacturing process or clinical context and therefore belong outside this model? boundary
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 is recall-based information; no sources or current standard editions were consulted.
- Hydration state and grade are independent distinctions; verify water content, assay and impurities for the intended application.
- Check current jurisdiction-specific GHS classifications, exposure limits and additive requirements; thermal values also require confirmation of hydration state and measurement conditions.
- Which of these check these first hold for the sense of citric acid this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Anhydrous citric acid
- Citric acid monohydrate
- Food-grade citric acid
- Pharmaceutical-grade citric acid
- Reagent-grade citric acid
- Technical-grade citric acid
- Which of these kinds and varieties hold for the sense of citric acid 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 - 77-92-9 - Anhydrous citric acid.
- CAS Registry Number - 5949-29-1 - Citric acid monohydrate.
- PubChem CID - 311 - Citric acid.
- EC number - 201-069-1 - Citric acid substance identity.
- Food additive numbering - E 330 / INS 330 - European E-number and Codex International Numbering System identifier.
- Which of these identifiers and schemes hold for the sense of citric acid this model covers, and on what evidence? provenance
Standards and regulation
Recalled without web access and unsourced; every item is a lead to verify.
- Food Chemicals Codex, published by USP: citric acid identity and purity specifications.
- United States Pharmacopeia-National Formulary, published by USP: compendial specifications for pharmaceutical citric acid.
- European Pharmacopoeia, published by EDQM of the Council of Europe: monographs for anhydrous citric acid and citric acid monohydrate.
- FAO/WHO Joint Expert Committee on Food Additives: citric acid food-additive specifications.
- Which of these standards and regulation hold for the sense of citric acid this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Acidulant and acidity regulator in foods and beverages.
- Component of citrate buffers used to control solution pH.
- Chelating ingredient in cleaning formulations and descaling products.
- Acid component in effervescent formulations containing bicarbonate or carbonate.
- Pharmaceutical excipient for formulation acidity and taste adjustment.
- Which of these real-world use hold for the sense of citric acid 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, anhydrous - 192.12 - g/mol
- Molar mass, monohydrate - 210.14 - g/mol
- Melting temperature, anhydrous - Approximately 153; decomposition accompanies or follows heating - °C
- Successive acid dissociation constants in dilute aqueous solution near 25 °C - pKa1 approximately 3.13; pKa2 approximately 4.76; pKa3 approximately 6.40 - dimensionless
- Stoichiometric water content of pure monohydrate - Approximately 8.57 - % by mass
- Which of these typical measurements hold for the sense of citric acid 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.
- Solid material and concentrated solutions can cause substantial eye irritation.
- Airborne dust can irritate the respiratory tract.
- Repeated exposure to acidic solutions can damage susceptible surfaces; compatibility depends on material, concentration and contact time.
- Reaction with carbonates or bicarbonates releases carbon dioxide and can pressurize closed containers.
- Confusing monohydrate with anhydrous material causes errors in mass-based dosing and solution preparation.
- Which of these failure modes and hazards hold for the sense of citric acid this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Food-additive labeling may identify citric acid by name, E 330 or INS 330, depending on jurisdiction.
- Food and pharmaceutical acceptability depends on the applicable local specifications and the supplied grade.
- Which of these regional variation hold for the sense of citric acid 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.
- Citrate - Citrate denotes deprotonated forms of citric acid; protonation state depends on solution pH.
- Sodium citrate - A sodium salt of citric acid, with sodium counterions and properties distinct from the free acid.
- Isocitric acid - A constitutional isomer with the same molecular formula but a different arrangement of the hydroxyl group.
- Ascorbic acid - Vitamin C is a chemically distinct compound with formula C6H8O6; it is not citric acid.
- Lemon juice - A biological mixture containing citric acid, water and numerous other constituents.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of citric acid this model covers, and on what evidence? provenance
What the second pass must settle
- Which authoritative identifier records should anchor anhydrous citric acid and citric acid monohydrate within this single registry entry?
- Which grade specifications and editions should provide the initial assay, water and impurity acceptance criteria?
- Which measured solubility, acid-dissociation and thermal datasets are sufficiently documented for the intended operating conditions?
- Which jurisdictions and applications must the initial hazard, exposure-limit and permitted-use research cover?
- What evidence should distinguish acceptable caking or hydration changes from changes requiring lot quarantine or retesting?