Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Methods of measuring concentrations of lead

  1. Jul 5, 2007 #1
    I will be investigating the concentration of lead in Henna, a traditional moroccan substance we apply to our hands, for my extended essay. In order to do so, I have to derive method(s) by which I can easily measure concentration of lead. If you have any idea, please let me know. Your methods do not have to apply to only henna, it can be anything, like blood, for instance.
    Thank you very much.
  2. jcsd
  3. Jul 7, 2007 #2
    You can try forming a hydroxide and titrating for that... Or maybe lead acetate or carbonate? I think lead carbonate precipitates in cold water, so you may want to make a solution of henna (we use it in India too), and try to precipitate the lead.
  4. Jul 7, 2007 #3


    User Avatar
    Homework Helper
    Education Advisor
    Gold Member

    Maybe some form of electro-reduction, like voltammetry?
  5. Jul 8, 2007 #4
    Thank you very much! Any more ideas?
  6. Jul 9, 2007 #5


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I would simplify the matrix by ashing the sample and then dissolve it back into strong nitric acid. Boil the nitric to dryness and bring the residue to a standard volume with very pure DI (or distilled) water. Add known amounts of this standard solution to a paper that has been impregnated with potassium chromate and dried. The lead will form an insoluble chromate on the paper. Rinse the paper with DI water to remove the interfering color and observe the yellow spot. The intensity will correlate with the concentration. Rough construction grade white paper works best. If you do not want to go through the trouble of preparing the paper, use a water test kit (strips) for lead.

    You will have to work out the details yourself (sample size, standard volume size, test aliquot size, intensity of color vs. concentration, etc...)
  7. Jul 9, 2007 #6
    Thank you Chemisttree!! chaoseverlasting, can you please elaborate on your idea? I'm confused as to how you can determine the concentration of lead by itself, when titration entails finding the amount of acid in a solution (lead acetate)...and so you're not finding the concentration of lead but acid :p
    Last edited: Jul 9, 2007
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook