chlorophyll
Enable an AI agent to identify chlorophyll in a material, assess its composition and condition, and choose justified measurement, handling or use actions.
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.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to identify chlorophyll in a material, assess its composition and condition, and choose justified measurement, handling or use actions.
Chlorophyll is a class of magnesium-chelated cyclic tetrapyrrole pigments (mainly chlorins; chlorophyll c is a porphyrin exception) that absorb visible to far-red light and serve as the primary photoreceptors of oxygenic photosynthesis, typically phytol-esterified and protein-bound in photosystems I and II.
It can be Assign or revise a chlorophyll identity using reference-backed analytical evidence.; Select an extraction and separation procedure appropriate to the target pigment forms and matrix.; Quantify specified chlorophyll forms or a declared total using a validated method.; Compare spectra and composition over time to investigate transformation or loss.; Select storage and handling conditions supported for the preparation and intended use.; Accept, reanalyse, reclassify or reject a preparation against explicit identity and quality criteria..
Distinguishing features
Compare chromatographic separation and spectral evidence with an identified reference to distinguish chlorophyll from a green material whose pigment is unknown.
Resolve pigment structure and central-metal identity when distinguishing chlorophyll from pheophytins or metal-substituted derivatives; a product name alone is insufficient.
Check substituent and esterification evidence against the proposed chlorophyll form when distinguishing it from chlorophyllides; do not assume one side-chain criterion covers every form.
Use form-specific spectral and structural evidence to distinguish chlorophyll forms from one another and from bacteriochlorophylls.
Distinguish chemically identified chlorophyll from an operational result such as total chlorophyll, a fluorescence estimate or a commercial extract designation.
Scope
+ Identification of chlorophyll forms and resolution of ambiguous chlorophyll labels
+ Composition and quantity of chlorophyll in isolated preparations, extracts and biological samples
+ Absorption and fluorescence observations with their measurement conditions
+ Chemical integrity, aggregation and association with a surrounding matrix
+ Evidence needed to select extraction, storage, analysis or use conditions
- Whole-organism taxonomy, physiology and health
- Chloroplast and photosystem architecture and operation
- Complete photosynthesis and pigment biosynthesis pathways
- Independent models of chlorophyll derivatives, bacteriochlorophylls and other pigments
- Finished food, supplement, cosmetic or pharmaceutical product specifications
- Ecosystem productivity and remote-sensing models that use chlorophyll as an input
Characteristics
- Pigment identity
- Named chlorophyll form, resolved mixture, unresolved chlorophyll fraction or identity unconfirmed Determines which reference material, analytical method and interpretation apply.
- Identity evidence
- Links to reference structures, standards, chromatograms, spectra and identification reports Makes a chlorophyll assignment auditable and distinguishes a label from a verified identity.
- Sample matrix and association
- Host sample, solvent, formulation or pigment-protein complex; association known or unresolved Provides the context needed to interpret measurements and select preparation conditions.
- Chlorophyll content
- mol/L, mg/L, mg/g or mass fraction, with named analytes, denominator and uncertainty Allows comparisons without confusing pigment concentration with tissue content or extract purity.
- Pigment composition
- Mass or mole fractions and explicitly defined ratios, including unresolved fractions Distinguishes changes in total content from changes in the pigment mixture.
- Absorption spectrum
- Absorbance versus wavelength in nm, with solvent or matrix, path length and temperature Supports identity and quantity assessments when the measurement context is retained.
- Fluorescence response
- Emission versus wavelength, instrument units or calibrated yield, with excitation and sample conditions Supports comparisons while keeping fluorescence response distinct from pigment amount and biological function.
- Chemical integrity
- Intact within method limits, transformed fraction detected, mixed or unresolved Determines whether the preparation still meets the identity and quality requirements of its intended use.
- Dispersion and aggregation
- Dissolved, associated, aggregated, precipitated or unresolved, with supporting observations Helps explain optical changes and whether a sampled aliquot represents the preparation.
- Exposure history
- Time-linked records of light, temperature, oxygen exposure, solvent and acidity where meaningful Supports interpretation of changes and decisions about continued storage or remeasurement.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Chlorophyll identity Establish what the chlorophyll designation refers to and how that assignment is supported.
An agent cannot choose a suitable assay or action while treating every chlorophyll label as the same chemical material.
Pigment form
Resolve named pigment forms, mixtures and unidentified fractions.
Supported form assignment
Record the proposed identity, structural reference and evidence that supports or limits the assignment.
- Does chlorophyll here denote a named molecular form, a mixture or an operationally measured fraction? definition
- Which reference material or structural evidence supports the assignment, and which alternatives remain unresolved? provenance
Derivative and label boundaries
Separate chemical identity from commercial or analytical naming conventions.
Label-to-composition boundary
Record whether a label denotes identified pigments or an extract specification. The JECFA chlorophylls specification includes magnesium chlorophylls, pheophytins and accompanying extract constituents. [JECFA chlorophylls specification](https://www.fao.org/fileadmin/user_upload/jecfa_additives/docs/Monograph1/Additive-128.pdf)
- Which constituents satisfy the adopted chlorophyll identity, and which require links to derivative or other-pigment models? boundary
- Is the chlorophyll designation taken from chemical identification, an assay definition or a supplier specification? provenance
Chlorophyll material context Locate the pigment within its source material and current preparation.
A pigment in tissue, a protein complex and a solvent extract requires different sampling and interpretation.
Source and preparation
Connect the current preparation to its biological or supplied origin.
Preparation lineage
Record source, sampling and processing steps that could affect the observed pigment composition.
- From which organism, tissue, culture or supplied batch was this chlorophyll preparation obtained? provenance
- Which extraction, purification and transfer steps separate the original material from the measured preparation? provenance
Matrix and association
Describe the pigment's immediate physical and chemical surroundings.
Observed association state
Record solvent or host matrix and evidence for association, aggregation or precipitation.
- Is the measured chlorophyll in tissue, associated with a complex, dispersed in a formulation or extracted into a specified solvent? definition
- What observations distinguish dissolved pigment from aggregation, precipitation or matrix scattering in this preparation? measurement
Chlorophyll analytical evidence Make pigment amounts and optical observations interpretable and comparable.
A reported chlorophyll value needs an analyte definition, measurement basis and method context before an agent can use it.
Content and composition
Define what is counted and how quantities or ratios were obtained.
Traceable pigment quantity
Record analytes, calibration, extraction recovery where established, uncertainty and reporting basis.
- Which pigment forms are included in the reported content, and is its basis extract volume, wet mass, dry mass or another denominator? measurement
- What calibration, recovery evidence and interference assessment support this value for the actual matrix? measurement
Optical response
Retain the conditions needed to interpret absorption and fluorescence.
Conditioned optical observation
Record spectra with measurement conditions and the limits of conclusions drawn from them.
- Under which solvent or matrix, temperature, path length, excitation and instrument settings were these spectra obtained? measurement
- What evidence permits the optical signal to support identity, concentration or functional interpretation in this sample? boundary
Chlorophyll integrity Track whether the pigment retains its assigned composition and usable condition.
An agent must distinguish chemical transformation from physical redistribution and measurement artefacts before acting on a changed signal.
Transformation evidence
Evaluate changes in identified pigment fractions and possible products.
Integrity assessment
Record detected changes, product assignments and unresolved explanations relative to a baseline.
- Which measured changes support chemical transformation rather than dilution, adsorption, precipitation or instrument drift? measurement
- Which transformation products have been identified, and how much of the original chlorophyll remains within analytical uncertainty? measurement
Exposure and stability
Connect preparation history to evidence about continued suitability.
Preparation-specific stability
Record exposure history and stability evidence without assigning a universal chlorophyll shelf life.
- What light, temperature, oxygen and chemical-environment exposures occurred between preparation and measurement? provenance
- Which stability observations justify a storage interval or trigger reanalysis for this pigment mixture and matrix? action
Chlorophyll action decisions Translate identity, matrix and integrity evidence into preparation and suitability decisions.
Recording chlorophyll is useful only if an agent can determine which next steps the evidence supports.
Extraction and analysis selection
Choose procedures compatible with the target pigment forms and the question being asked.
Fit-for-purpose procedure
Record why an extraction or assay is appropriate and what it may leave unresolved.
- Which procedure recovers and distinguishes the target chlorophyll forms in this matrix with demonstrated performance? action
- Could the proposed preparation change the pigment identity or association state that the task needs to preserve? boundary
Use and disposition
Decide whether the preparation satisfies an explicitly stated application.
Evidence-based disposition
Connect intended use to identity, content, integrity and matrix criteria, linking broader product requirements to their owning models.
- What chlorophyll identity, composition, concentration and integrity criteria must this preparation meet for its intended use? action
- Does the evidence support acceptance, reanalysis, further purification, reclassification or rejection? 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.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- chlorophyll a (universal in oxygenic phototrophs)
- chlorophyll b (plants, green algae, some cyanobacteria)
- chlorophyll c (c1, c2, c3; diatoms, dinoflagellates, brown algae and related chromophytes)
- chlorophyll d (some cyanobacteria, notably Acaryochloris)
- chlorophyll f (far-red cyanobacteria)
- divinyl chlorophyll a and b (Prochlorococcus)
- chlorophyll a' (C13² epimer; photosystem I reaction-centre cofactor)
- chlorophyllides (dephytylated forms; biosynthetic and extraction intermediates)
- Which of these kinds and varieties hold for the sense of chlorophyll this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Wikidata - Q104931 (chlorophyll as a class); Q104847 (chlorophyll a) - Class item plus the principal congener; other congeners have separate items.
- CAS Registry Number - 479-61-8 (chlorophyll a); 519-62-0 (chlorophyll b); 1406-65-1 (chlorophyll, unspecified/commercial mixture) - Use the congener-specific CAS in analysis; 1406-65-1 is the bulk/extract number.
- ChEBI - CHEBI:27891 (chlorophyll); CHEBI:28966 (chlorophyll a) - ChEBI treats chlorophyll as a role/parent and lists named congeners as children.
- MeSH - D002734 - U.S. National Library of Medicine heading Chlorophyll.
- Codex INS / EU E-number - INS 140 / E140 (chlorophylls); INS 141 / E141 (copper complexes of chlorophylls / chlorophyllins) - Food-colour identity, not a chemical synonym for native leaf chlorophyll.
- IUPAC-IUB tetrapyrrole trivial names - chlorophyll a, a', b, c1, c2, c3, d, f (and divinyl variants) - The names used in biochemistry and pigment chromatography.
- Which of these identifiers and schemes hold for the sense of chlorophyll this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- IUPAC-IUB Joint Commission on Biochemical Nomenclature, Nomenclature of tetrapyrroles (Recommendations 1986) - IUPAC / IUBMB
- ISO 10260:1992 Water quality - spectrometric determination of chlorophyll-a concentration - International Organization for Standardization
- UNESCO/SCOR phytoplankton-pigment methodology (Jeffrey, Mantoura and Wright, 1997) - UNESCO
- U.S. EPA Method 445.0 (fluorescence) and Method 446.0 (spectrophotometric) for chlorophyll a and pheophytin a in water - U.S. Environmental Protection Agency
- Codex Alimentarius INS 140 and INS 141 with JECFA specifications - FAO/WHO
- EU food additives E140 and E141: Regulation (EC) No 1333/2008 (authorisation) and Commission Regulation (EU) No 231/2012 (purity criteria) - European Commission
- 21 CFR 73.125 sodium copper chlorophyllin as a colour additive - U.S. Food and Drug Administration
- Which of these standards and regulation hold for the sense of chlorophyll this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Leaf and canopy chlorophyll as a nitrogen/status proxy in agronomy (SPAD and related optical meters; remote-sensing vegetation indices).
- Chlorophyll a concentration as the standard biomass/trophic indicator in lakes, reservoirs and the ocean, including satellite ocean-colour products.
- HPLC pigment suites (Chl a, b, c, divinyl Chl a) to assign phytoplankton taxa in oceanography.
- Food colour: spinach/alfalfa extracts (E140) and copper chlorophyllins (E141) in confectionery, beverages and processed foods.
- Consumer "liquid chlorophyll" and deodorant/breath products, almost always sodium copper chlorophyllin rather than native chlorophyll.
- Isolation of pigment-protein complexes and reaction centres in photosynthesis research; Chl a' as a PSI marker.
- Industrial extraction from leafy biomass (and, in parts of East Asia, silkworm faeces) for colour and chlorophyllin manufacture.
- Which of these real-world use hold for the sense of chlorophyll this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Qy absorption maximum of chlorophyll a in 90% acetone - 662-665 - nm
- Surface-ocean / lake chlorophyll a concentration - 0.02-10 typical; oligotrophic <0.1, blooms often 10-100+ - mg m^-3
- Leaf chlorophyll content (vascular plants) - 0.5-3.5 mg g^-1 fresh mass, or about 200-800 mg m^-2 - mg g^-1 FW or mg m^-2
- Chlorophyll a/b molar ratio in C3 leaves - about 2.2-2.8 (shade) to 3.2-4.2 (sun) - mol mol^-1
- Maximum quantum efficiency of PSII (Fv/Fm) in unstressed leaves - 0.75-0.83 - dimensionless
- Handheld chlorophyll meter (SPAD-type) on crop leaves - about 20-60 in healthy crops, cultivar-dependent - SPAD units
- Which of these typical measurements hold for the sense of chlorophyll this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Acid-catalyzed loss of central Mg to pheophytin (olive discoloration of acid-canned vegetables; also an analytical artefact).
- Chlorophyllase dephytylation and allomerization/epimerization (a → a') during tissue damage, extraction or storage, biasing HPLC and spectrophotometric assays.
- Photo-oxidative bleaching and singlet-oxygen formation when chlorophyll is unbound or photosystems are over-reduced (photodamage, pigment loss).
- Nutrient chlorosis (N, Mg, Fe) lowering content without a change in pigment identity.
- High water-column chlorophyll a marks eutrophication and bloom risk; associated hypoxia or cyanotoxins are from the bloom, not from the pigment itself.
- Native chlorophyll is lipid-soluble and unstable in light/acid; products labelled "chlorophyll" are often copper chlorophyllin, which is a different, more stable species.
- Which of these failure modes and hazards hold for the sense of chlorophyll this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- EU authorises chlorophylls (E140) and copper chlorophyllins (E141) as food colours more broadly than the U.S., where FDA listing is essentially sodium copper chlorophyllin in limited uses.
- East Asian commercial "chlorophyll" drinks and extracts are typically chlorophyllin salts; some Chinese production uses silkworm faeces (can sha) as feedstock.
- Agronomy talks almost only of chlorophyll a+b; cyanobacterial and Japanese seaweed research routinely distinguish chlorophyll d and f.
- Ocean-colour algorithms and extraction solvents (acetone vs methanol vs ethanol) differ by region and water type (open-ocean Case-1 versus coastal/inland Case-2), so reported "chlorophyll a" is not fully interchangeable.
- Reported historical "chlorophyll e" is not a structurally accepted kind in current pigment lists.
- Which of these regional variation hold for the sense of chlorophyll this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- bacteriochlorophyll a (and other BChls) - Bacteriochlorin with two reduced rings; Qy near 770 nm in solvent versus ~662-665 nm for Chl a; confined to anoxygenic phototrophs.
- pheophytin a - Central Mg absent; mild acidification converts Chl a to pheophytin a (EPA 445.0 acid test) and HPLC retention/visible spectrum shift (band near 535 nm).
- sodium copper chlorophyllin (E141) - Saponified, often Cu-substituted, water-soluble derivative; aqueous solubility and Cu (not Mg) distinguish it from acetone-extractable native chlorophyll.
- heme (protoheme IX) - Iron porphyrin, not a magnesium chlorin; no intense red Qy of chlorophyll and a different protein context (cytochromes/globins vs photosystems).
- protochlorophyllide / chlorophyllide a - Phytol chain absent (and Pchlide is not reduced at C17-C18); NADPH:protochlorophyllide oxidoreductase substrate versus mature Chl a on HPLC.
- carotenoids (e.g. β-carotene, fucoxanthin) - Accessory hydrocarbons/xanthophylls with no Mg and no chlorophyll-type Qy band; separated by HPLC and by absence of the red absorption used for Chl a assays.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of chlorophyll this model covers, and on what evidence? provenance
Sources
- Nomenclature of tetrapyrroles (Recommendations 1986) - Specialist definition of chlorophylls as Mg tetrapyrroles, trivial names (a, a', b, c, d), and distinction from bacteriochlorophylls, pheophytins and chlorophyllides (IUPAC-IUB Joint Commission on Biochemical Nomenclature; Pure Appl. Chem. 1987 / Eur. J. Biochem. 1988).
- An Overview of Chlorophylls and Bacteriochlorophylls: Biochemistry, Biophysics, Functions and Applications - Kinds in use (a, b, c, d, f, divinyl forms), spectroscopic ranges, biosynthetic neighbours, and functional placement in photosystems (Hugo Scheer, in Grimm et al., Springer, 2006).
- Phytoplankton Pigments in Oceanography: Guidelines to Modern Methods - Oceanographic practice: chlorophyll a as biomass proxy, HPLC separation from pheophytins and chlorophyll c, extraction artefacts, and typical seawater concentration ranges (Jeffrey, Mantoura and Wright, UNESCO, 1997).
- ISO 10260:1992 Water quality - Measurement of biochemical parameters - Spectrometric determination of the chlorophyll-a concentration - Standard spectrometric method and reporting unit for chlorophyll a in water (International Organization for Standardization).
- Method 445.0: In Vitro Determination of Chlorophyll a and Pheophytin a in Marine and Freshwater Algae by Fluorescence - Fluorescence assay, acidification test that separates chlorophyll a from pheophytin a, and routine water-quality use (U.S. Environmental Protection Agency).
- Commission Regulation (EU) No 231/2012 laying down specifications for food additives (E140 chlorophylls; E141 copper complexes of chlorophylls) - Food-additive identity, purity, and the legal split between native chlorophylls and copper chlorophyllins (European Commission; with authorisation under Regulation (EC) No 1333/2008).
- 21 CFR 73.125 Sodium copper chlorophyllin - U.S. colour-additive listing for the water-soluble copper derivative, which is narrower than EU E140/E141 practice (U.S. Food and Drug Administration).
- Molecular Mechanisms of Photosynthesis - Reaction-centre versus antenna roles, Chl a/a' in PSI, absorption of d and f in far-red cyanobacteria, and photodamage when excitation is not quenched (Robert E. Blankenship, Wiley-Blackwell).
What the second pass must settle
- Which chlorophyll forms and naming conventions should this registry entry explicitly encompass, given its missing definition and possible neighbouring entries?
- Which existing Vercy models already own chlorophyll, chlorophyllides, pheophytins, chlorophyllins or bacteriochlorophylls, and where should this entry link instead of duplicating ownership?
- Which analytical methods and reference materials adequately distinguish the included pigment forms and their transformation products in each intended matrix?
- What preparation-specific evidence establishes acceptable exposure conditions, storage intervals and integrity thresholds?
- Under what validated conditions may chlorophyll content or fluorescence support a biological interpretation, and which conclusions must remain with host-organism or photosystem models?