rubeanic acid

ru·be·an·ic ac·id

(rū'bē-an'ik as'id),
Dithiooxamide, which forms complete dark greenish-black complexes with copper in alkaline ethanolic solution; used histochemically for demonstrating pathologic copper deposits, as in Wilson disease; also reacts with cobalt and nickel.
References in periodicals archive ?
Calcium oxalate in this case was confirmed by the rubeanic acid stain of Yasue.
Perhaps the most reliable method, and the one used in this study, is the Yasue stain, which applies aqueous silver nitrate and rubeanic acid to color oxalate black.