Alizarin complexone С19H15NO8 (N-(3,4-Dihydroxy-2-anthraquinonylmethyl)iminodiacetic acid; Alizarin-3-methylamine-N,N-diacetic acid; CAS No.: 3952-78-1) is a crystalline powder of a yellow-brown color with a melting point of 179-180 deg. C, insoluble in water; is soluble in dimethylformamide, pyridine, aqueous solutions of alkalis.
Alizarin complexone is a reagent for the photometric determination of F- as a ternary complex with La or Ce in water-dimethylformamide medium at pH 3.6-4.2.
Alizarin complexone is a metallochrome indicator for the titrimetric determination of Ba, Ca, Cd, Sr at pH 10.0 (color transition from blue to red); Cu, Pb, In, Zn at pH 4.0 (color transition from red to yellow).