Copper 8-hydroxyquinoline (copper oxinate, copper quinolinolate, CAS 10380-28-6) is a yellow-green crystalline powder supplied at 98% minimum content, with tight limits on chloride, sulphate and moisture. It is a chelated organic copper compound – the copper ion locked into two 8-hydroxyquinoline ligands – used as an agricultural fungicide and bactericide, and as an industrial preservative in coatings, plastics, textiles and timber.

Specification

Parameter	Limit	Why it matters
Appearance	Yellow-green crystal powder	The colour is characteristic of the chelate; a brown or dull cast suggests free copper or degraded ligand
Content	98% min	The chelated copper content – the figure the formulator doses on
Chloride (Cl)	0.01% max	Critical for agricultural use. Chloride is the classic cause of leaf burn with copper sprays, and it also drives corrosion in coatings and in processing equipment
Sulphate (SO4)	0.1% max	Residual from the copper salt used in manufacture; affects formulation stability and phytotoxicity
Loss on drying	0.5% max	Moisture affects storage stability, dispersibility in wettable powders and the assay basis

Identity and properties

Property	Value	Practical significance
Chemical name	Bis(8-hydroxyquinolinato)copper(II)	Two 8-hydroxyquinoline ligands coordinating one copper ion through nitrogen and oxygen
Formula / molecular weight	C18H12CuN2O2 / about 352	Copper is roughly 18% of the molecule by mass
Appearance	Yellow-green crystalline powder	Distinct from the blue of inorganic copper salts – a useful visual identity check
Solubility	Essentially insoluble in water; sparingly soluble in organic solvents	Formulated as wettable powders and suspensions rather than solutions
Stability	Stable in normal storage; decomposes in strong acid with release of the ligand	Do not formulate with strongly acidic components
Copper release	Slow, because the copper is chelated	This is the source of its main advantage over inorganic copper – see below

Why chelated copper behaves differently

Aspect	Copper 8-hydroxyquinoline	Inorganic copper (Bordeaux, copper hydroxide, copper oxychloride)
Copper availability	Chelated – released gradually	Largely free ionic copper at application
Phytotoxicity	Lower; less risk of leaf burn and fruit marking	Higher, particularly in cool wet conditions and on sensitive crops
Use rate	Lower, because the active is more efficient per unit of copper	Higher, and limited by annual copper loading rules
Chloride sensitivity	Controlled in the specification precisely because of this	Depends on the salt used
Cost	Higher per kilogram	Lower, which is why inorganic copper still dominates by volume
Formulation	Wettable powder, suspension concentrate	Wettable powder, suspension, Bordeaux mixture prepared on farm

The commercial logic: chelated copper is chosen where crop safety matters more than cost per kilogram – young tissue, sensitive varieties, and programmes already close to their annual copper limit.

Applications

Sector	Function	Formulation note
Agricultural fungicide and bactericide	Protectant against fungal and bacterial disease on fruit, vegetables and field crops	Wettable powder and suspension; the grade must meet the registration requirements of the destination market
Industrial preservation of coatings	Anti-mould and anti-algal additive for paints and renders	Compatibility with the binder system and with other biocides has to be checked
Plastics and polymers	Preservative against fungal growth in flexible PVC and similar materials	Thermal stability during processing is the constraint
Textiles and leather	Rot and mould resistance	Often applied in a treatment bath rather than as an additive
Timber	Wood preservative component	Fixed in the wood rather than leached, which is the point of using a chelate
Antifouling coatings	Barnacle and algae control on hulls and structures	Registration and discharge rules vary widely between markets

Regulatory position

Framework	What applies	What the buyer must confirm
Pesticide registration	Agricultural use requires registration in the destination country, with the label defining permitted crops, rates and intervals	That the product is registered for your crop and market – an unregistered use is not made lawful by the raw material being available
Biocidal products	Industrial preservation uses are regulated as biocidal products in many markets	The product type and whether authorisation exists for that use
Copper loading limits	Several markets cap total copper applied per hectare per year, particularly in organic production	Whether chelated copper counts towards the cap in your market, and at what rate
Organic certification	Copper compounds are restricted rather than freely permitted in organic systems	Whether this specific compound is listed by the certifier you work with – do not assume
Transport and storage	Classified as a hazardous substance for transport in many jurisdictions	The classification and packaging your market applies

Note on claims. We supply the technical material. We do not make efficacy claims and we do not advise on crop use – the label and the registration, held by the marketing authorisation holder, define what may be claimed and how the product may be applied. Tell us the destination market and end use at enquiry so the documentation can be matched to it.

Packaging, storage and documentation

Item	Detail
Packaging	25 kg fibre drums or paper sacks with PE liner; smaller packs on request
Storage	Cool, dry, sealed, away from acids and foodstuffs. The powder is stable but hygroscopic at the surface; keep the liner closed
Documentation	Batch COA (content, chloride, sulphate, loss on drying, appearance) plus SDS
Grade statement	Technical or agricultural grade as agreed; confirm the registration status your market requires