Checking several chemical measurement processes, I found an active reagent that applies, it is named: "Diphenylthiocarbazone (or Dithizone)". It reacts with most of heavy metal ions, binding to Cu, Zn, Cd, Hg, Pb, Mn, Co, Ni. I believe that we will get a color indicator in the water sample that could be measured by colorimetry (or spectrophotometry by reflectance).
Not sure how it behaves under our condition at Rio Paraopeba, where we find multiple contaminants in the same water sample. Hopefully able to separate it using analytics comparing it with standard measurements by element.
What is your opinion, does this idea of using this chemical reagent sound like a feasible solution. Some documentation I found here [ https://core.ac.uk/download/pdf/78563164.pdf ]
Looking forward to hear your opinion.