1982 Volume 31 Issue 9 Pages 545-547
The effects of metal ions on the colorimetric determination of cyanogen chloride with pyridine-pyrazolone and isonicotinic acid-pyrazolone methods were examined. Colors were allowed to develop at 25°C for 30 min after the color-producing reagent was mixed with the test solutions of metal ion and cyanogen chloride. In the presence of Cu (II) ion at higher concentrations beyond 2μg/50 ml, the initial blue color of the test solution faded gradually to red in pyridine method and to yellow-green in isonicotinic acid method. This interference could be eliminated by adding a EDTA solution in sufficient amounts to complex Cu (II) ion. EDTA was also used to prevent the formation of the precipitates of metal hydroxides under the colorimetric conditions. It was possible to determine cyanogen chloride in samples containing metal ions in concentrations up to 10 mg/50 ml for Cd (II), Co (II), Mn (II), Ni (II), Pb (II), and Zn (II), and up to 1 mg/ 50 ml for Cr (III) and Fe (II, III).
