We have tested substances as 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.