A SPOT TEST FOR CADMIUM JOHN F. PETROCCIONE River Dell Regional High Schwl, Oradell, N. I.
FAILURE to complex the copper ion completely in the analysis of Group IIA has offered some difficulty t o the beginner in his subsequent test for the cadmium ion. A simple but effective spot test can be made with Titan yellow. A drop of the ammoniacal coppercadmium mixture is placed on a piece of filter paper and to this is added a drop of Titan yellow reagent. A bright red-orange coloration is a positive test for the cadmium ion. Concentrations of copper normally
found in such mixtures offer no interference. Other ions of Group I1 (on filter paper) produce varying shades of orange upon exposure to ammonia fumes. However, the red-orange produced by the cadmium ion is unmistakable. The reagent is prepared by dissolving 0.2 g. of Titan yellow in 70 ml. of methyl alcohol and diluting t o 100 ml. with distilled water.
JOURNAL OF CHEMICAL EDUCATION
