Copper(II) citrate is the copper(II) salt of citric acid that occurs in several hydration states. Commercial material is commonly a blue-green solid and is used as a source of copper in industrial, agricultural and some supplement applications.
The anhydrous powder is blue while the hydrate is a light green.
Copper(II) citrate can be prepared by reacting a soluble copper(II) salt such as copper(II) sulfate with trisodium citrate or tripotassium citrate; different hydrate stoichiometries may be isolated depending on conditions.
Copper(II) citrate is used as a copper source in some agricultural micronutrient formulations and in proprietary supplement formulations. It is also used as a reagent and copper source in industrial and research contexts.