Question

Would flame test be useful for detecting metal ions present in a mixture of metal ions?

Answer 1

It all depends upon what metals are in the material as well as which ones you wish to detect as well as what you are using as a detector. In most situations, the answer is no, expecially if the eye is the detector; however, in some simple mixtures it is possible. For example, Na and K can be determined if they are together and Cu can be detected in some mixtures. There are a few other examples. Probably, if I know the "spirit" of the question, the answer generally is no. If one uses a spectrograph as a detector instead of the human eye, then it is possible to detect (and even quantitatively determine) several elements that constitute a mixture.