Any measurement of copper, an essential dietary trace element, atomic number 29, involved in the formation of bone and blood as a necessary component of several enzymes, in liver, the large, dark-red organ located in the cranial portion of the abdomen of vertebrates, just behind or below the diaphragm, the functions of which include storage and filtration of blood; secretion of bile; detoxification of noxious substances; conversion of sugars into glycogen; synthesis and breakdown of fats and temporary storage of fatty acids; and synthesis of serum proteins.