Indium complexes cyanides

To detect indium in the presence of zinc, nickel, cohalt, manganese, which also give color lakes resistant to boric acid, these ions are converted to the corresponding unreactive complex cyanide ions. The paper impregnated with the dye is treated with a drop of 5 % potassium cyanide, followed by a drop of the test solution, and then another drop of the cyanide solution. After immersion in boric acid, the characteristic stain due to indium remains on the paper. The following sensitivities were obtained, using this procedure on a drop (0.025 ml) ... 

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