We have tested substances as follows from substances Iron(III)(aq) and nickel(II) (aq).We can find the contaminants from comparing the pattern of absorption spectra of the pure substance contaminant that absorbs more of a particular wavelength (or range of wavelength).
The pure substances the shapes of these curves will be changed. The pure substances that wasn’t there for change in a wider range of wavelengths to higher or lower levels. If the entire curve of the suspect. It is likely due to a concentration difference and not a contaminant. In that case, the color of the material and their solutions may still be visibly different but it will not show up in the spectra.