Zincon is a colorimetric reagent for Zn and Cu detection, and a metal indicator in EDTA titration. This reagent is insoluble in organic solvents, but slightly soluble in water and alcohol. Its proton dissociation constants are reported to be pKa1=7.9-8.3, pKa2=7.9-8.3 and pKa3=13-14. The aqueous solution of Zincon is yellow or orange-yellow in weak alkaline conditions, and turns blue in the presence of Cu (maximum wavelength: 600 nm, molar absorptivity: 1.9×104) and Zn (pH 8.5-9.5, maximum wavelength: 620 nm, molar absorptivity: 23,000). Dr. Koupparis and others used Zincon for the automated flow injection spectrometric determination of 1-10 mg per ml levels of Zn at 80 samples per hour. The detection limit was reported to be 0.05 μg per ml.
Chelate titration: Ca, Cd, Hg, Pb, Zn
Colorimetry: Cu, Zn
K.Yoshimura, et al., Talanta, 25, 579 (1978);
G. Ackermann, et al., Talanta, 26, 693 (1979);
K. Yoshimura, et al., Talanta, 32, 345 (1985);
M. A. Koupparis, et al., Analyst, 111, 1311 (1986);
C. M. Corns, et al., Ann. Clin. Biochem., 24, 591 (1987);
E. Hilario, et al., J. Biochem. Biophys. Methods, 21, 197 (1990);
R. Liu, et al., Analyst, 120, 569 (1995);
P. Richter, et al., Analyst, 122, 1045 (1997);
M. P. Cuajungco, et al., Brain Res., 799, 97 (1998).