[dama]

I have an unknown solution of Cobalt Sulfate, Copper Chloride, and/or Nickel Chloride. I want to qualitatively identify which metals are present in solution. I have tried reacting the solution with dimethylglyoxime to test for Ni, but the result is a brownish solution (instead of bright red). Is that color due to the presence of Co²⁺ ions?

Also, if I were to create standard solutions of the various metal ions, e.g. "Cobalt + Copper" or "Copper + Nickel", and then add ammonium hydroxide to those. Can I compare the color of the standards to the color of my unknown solution + NH₄OH? I'm not sure if the concentrations would mess up the tests?

Thanks for your he_lp! Any other suggestions on how to identify which metals are present are appreciated too 

[AWK]

Add some ammonia to your sample before test with DMG. Add  about 1 ml DMG solution to test tube slowly, and do not mix solution (then cobalt and copper do not mask color). Nickel gives a strawberry red colored ring at the surface of solution.

Test for color are rather useless. Color of copper predominates in solution of these salts and their ammonia complexes.

Test for Cu in this mixture.
Add some KI and then extract I2 to CCl4 or CHCl3 - violet color of lower layer

Test for Co
Add solid NH4SCN to your sample, some Na2S2O3 to mask copper, and extract Co(SCN)2 to amyl alcohol (eventually butyl alcohol - alcohol cannot form a homogenous solution with water)  - nice blue upper layer